All parsing null to be TFP or TMP

Insert a TypePtr/TypeNil around TypeMemPtr and TypeFunPtr in the lattice; allows the parsing of "null" to mean either a TMP or TFP null. Cleanup Type null checks and several prints. Drop Type.lub, Type.makeInit. Add a Parser NIL & ZERO. Clean up parser errors, track line numbers for future parser errors.
author: Cliff Click <cliffc@acm.org> 2024-12-21 16:43:03 -0800
committer: Cliff Click <cliffc@acm.org> 2025-01-15 15:07:30 -0800
commit: 8095c50f846699f7570bdea4c6517653c5795c2e (patch)
tree: 1d5ed8477dd796766a3a6aa7b6c5d2e6cb883946 /chapter18
parent: b0b26bd248fad6f6d2ac23f673ae73095cd5c3cb (diff)
download: Simple-8095c50f846699f7570bdea4c6517653c5795c2e.tar.gz
Simple-8095c50f846699f7570bdea4c6517653c5795c2e.zip
51 files changed, 1606 insertions, 429 deletions
diff --git a/chapter18/Makefile b/chapter18/Makefile
index 0be7b659..f42659de 100644
--- a/chapter18/Makefile
+++ b/chapter18/Makefile
@@ -68,7 +68,8 @@ JVM=nice java -ea -cp "build/classes/main${SEP}${jars}${SEP}$(CLZDIR)/test"
 
 tests:	$(default_targets)
 	@echo "testing " $(test_cp)
-	@$(JVM) org.junit.runner.JUnitCore $(test_cp) com.seaofnodes.simple.FuzzerWrap
+	@$(JVM) org.junit.runner.JUnitCore $(test_cp)
+	@$(JVM) org.junit.runner.JUnitCore com.seaofnodes.simple.FuzzerWrap
 
 fuzzer: $(default_targets)
 	@echo "fuzzing " $(test_cp)
diff --git a/chapter18/docs/lattice.gv b/chapter18/docs/lattice.gv
index 4a8b1d4c..f8af5718 100644
--- a/chapter18/docs/lattice.gv
+++ b/chapter18/docs/lattice.gv
@@ -3,7 +3,8 @@ digraph Lattice {
     // Define nodes
     splines=false;
     node [shape=circle, style=filled];
-    nodesep=0.6;
+    nodesep=0.2;
+    ranksep=0.2;
 
     TOP [label=<<B>⊤</B >>, fillcolor=black, fontcolor=white];
     BOT [label=<<B>⊥</B>>, fillcolor=black, fontcolor=white];
@@ -22,13 +23,13 @@ digraph Lattice {
     INT_TOP [label=<<B>⊤</B >:int>, fillcolor=lightblue, shape=oval];
     INT_BOT [label=<<B>⊥</B>:int>, fillcolor=lightblue, shape=oval];
 
-    INT_HI    [label="max < min" , fillcolor=lightblue, shape=oval];
-    INT_XBOOL [label="1...0", fillcolor=lightblue, shape=oval];
+    INT_HI    [label="[min>max]" , fillcolor=lightblue, shape=oval];
+    INT_XBOOL [label="[1...0]", fillcolor=lightblue, shape=oval];
     INT_CON   [label="constants", fillcolor=lightblue, shape=oval];
     INT_CON0  [label="0", fillcolor=lightblue];
     INT_CON1  [label="1", fillcolor=lightblue];
-    INT_BOOL  [label="0...1", fillcolor=lightblue,shape=oval];
-    INT_LO    [label="max > min" , fillcolor=lightblue, shape=oval];
+    INT_BOOL  [label="[0...1]", fillcolor=lightblue,shape=oval];
+    INT_LO    [label="[min<max]" , fillcolor=lightblue, shape=oval];
 
     TOP        -> INT_TOP;
     INT_TOP    -> INT_HI;
diff --git a/chapter18/docs/lattice.svg b/chapter18/docs/lattice.svg
new file mode 100644
index 00000000..030f4826
--- /dev/null
+++ b/chapter18/docs/lattice.svg
@@ -0,0 +1,691 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 12.2.0 (20241103.1931)
+ -->
+<!-- Title: Lattice Pages: 1 -->
+<svg width="1330pt" height="584pt"
+ viewBox="0.00 0.00 1329.51 583.54" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 579.54)">
+<title>Lattice</title>
+<polygon fill="white" stroke="none" points="-4,4 -4,-579.54 1325.51,-579.54 1325.51,4 -4,4"/>
+<!-- TOP -->
+<g id="node1" class="node">
+<title>TOP</title>
+<ellipse fill="black" stroke="black" cx="641.51" cy="-554.42" rx="21.12" ry="21.12"/>
+<text text-anchor="start" x="633.63" y="-549.99" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00" fill="white">⊤</text>
+</g>
+<!-- XCTRL -->
+<g id="node3" class="node">
+<title>XCTRL</title>
+<ellipse fill="yellow" stroke="black" cx="36.51" cy="-492.79" rx="36.51" ry="18"/>
+<text text-anchor="start" x="17.76" y="-488.74" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊤</text>
+<text text-anchor="start" x="33.51" y="-488.74" font-family="Times New Roman,serif" font-size="14.00">:ctrl</text>
+</g>
+<!-- TOP&#45;&gt;XCTRL -->
+<g id="edge1" class="edge">
+<title>TOP&#45;&gt;XCTRL</title>
+<path fill="none" stroke="black" d="M620.33,-551.33C533.82,-542.8 206.01,-510.5 83.28,-498.4"/>
+<polygon fill="black" stroke="black" points="83.86,-494.94 73.56,-497.44 83.17,-501.91 83.86,-494.94"/>
+</g>
+<!-- INT_TOP -->
+<g id="node5" class="node">
+<title>INT_TOP</title>
+<ellipse fill="lightblue" stroke="black" cx="316.51" cy="-492.79" rx="33.95" ry="18"/>
+<text text-anchor="start" x="299.63" y="-488.74" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊤</text>
+<text text-anchor="start" x="315.38" y="-488.74" font-family="Times New Roman,serif" font-size="14.00">:int</text>
+</g>
+<!-- TOP&#45;&gt;INT_TOP -->
+<g id="edge4" class="edge">
+<title>TOP&#45;&gt;INT_TOP</title>
+<path fill="none" stroke="black" d="M620.68,-549.6C568.33,-539.99 430.36,-514.68 359.64,-501.71"/>
+<polygon fill="black" stroke="black" points="360.44,-498.29 349.97,-499.93 359.18,-505.18 360.44,-498.29"/>
+</g>
+<!-- FLT_TOP -->
+<g id="node14" class="node">
+<title>FLT_TOP</title>
+<ellipse fill="aqua" stroke="black" cx="494.51" cy="-492.79" rx="32.41" ry="18"/>
+<text text-anchor="start" x="478.76" y="-488.74" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊤</text>
+<text text-anchor="start" x="494.51" y="-488.74" font-family="Times New Roman,serif" font-size="14.00">:flt</text>
+</g>
+<!-- TOP&#45;&gt;FLT_TOP -->
+<g id="edge18" class="edge">
+<title>TOP&#45;&gt;FLT_TOP</title>
+<path fill="none" stroke="black" d="M621.99,-545.5C598.79,-536.09 559.6,-520.19 530.78,-508.5"/>
+<polygon fill="black" stroke="black" points="532.29,-505.34 521.7,-504.82 529.65,-511.82 532.29,-505.34"/>
+</g>
+<!-- PTR -->
+<g id="node22" class="node">
+<title>PTR</title>
+<polygon fill="none" stroke="none" points="668.51,-519.29 614.51,-519.29 614.51,-466.29 668.51,-466.29 668.51,-519.29"/>
+<polygon fill="green" stroke="none" points="623.51,-492.79 623.51,-515.29 659.51,-515.29 659.51,-492.79 623.51,-492.79"/>
+<polygon fill="none" stroke="black" points="623.51,-492.79 623.51,-515.29 659.51,-515.29 659.51,-492.79 623.51,-492.79"/>
+<text text-anchor="start" x="630.63" y="-498.99" font-family="Times New Roman,serif" font-size="14.00" fill="white">*ptr</text>
+<polygon fill="lightgreen" stroke="none" points="623.51,-470.29 623.51,-492.79 659.51,-492.79 659.51,-470.29 623.51,-470.29"/>
+<polygon fill="none" stroke="black" points="623.51,-470.29 623.51,-492.79 659.51,-492.79 659.51,-470.29 623.51,-470.29"/>
+<text text-anchor="start" x="626.51" y="-476.49" font-family="Times New Roman,serif" font-size="14.00">struct</text>
+</g>
+<!-- TOP&#45;&gt;PTR -->
+<g id="edge33" class="edge">
+<title>TOP&#45;&gt;PTR</title>
+<path fill="none" stroke="black" d="M641.51,-532.9C641.51,-532.06 641.51,-531.22 641.51,-530.37"/>
+<polygon fill="black" stroke="black" points="645.01,-530.61 641.51,-520.61 638.01,-530.61 645.01,-530.61"/>
+</g>
+<!-- STRUCT_TOP -->
+<g id="node24" class="node">
+<title>STRUCT_TOP</title>
+<ellipse fill="lightgreen" stroke="black" cx="746.51" cy="-492.79" rx="44.7" ry="18"/>
+<text text-anchor="start" x="721.76" y="-488.74" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊤</text>
+<text text-anchor="start" x="737.51" y="-488.74" font-family="Times New Roman,serif" font-size="14.00">:struct</text>
+</g>
+<!-- TOP&#45;&gt;STRUCT_TOP -->
+<g id="edge36" class="edge">
+<title>TOP&#45;&gt;STRUCT_TOP</title>
+<path fill="none" stroke="black" d="M659.8,-543.03C674.04,-534.94 694.24,-523.47 711.55,-513.64"/>
+<polygon fill="black" stroke="black" points="713.07,-516.81 720.03,-508.83 709.61,-510.72 713.07,-516.81"/>
+</g>
+<!-- MEM_TOP -->
+<g id="node29" class="node">
+<title>MEM_TOP</title>
+<ellipse fill="blue" stroke="black" cx="998.51" cy="-492.79" rx="43.67" ry="18"/>
+<text text-anchor="start" x="974.51" y="-488.74" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00" fill="white">⊤</text>
+<text text-anchor="start" x="990.26" y="-488.74" font-family="Times New Roman,serif" font-size="14.00" fill="white">:mem</text>
+</g>
+<!-- TOP&#45;&gt;MEM_TOP -->
+<g id="edge46" class="edge">
+<title>TOP&#45;&gt;MEM_TOP</title>
+<path fill="none" stroke="black" d="M662.51,-549.91C717.64,-540.7 867.72,-515.64 947.33,-502.34"/>
+<polygon fill="black" stroke="black" points="947.77,-505.82 957.06,-500.72 946.62,-498.91 947.77,-505.82"/>
+</g>
+<!-- TUPLE_TOP -->
+<g id="node34" class="node">
+<title>TUPLE_TOP</title>
+<ellipse fill="pink" stroke="black" cx="1182.51" cy="-492.79" rx="42.65" ry="18"/>
+<text text-anchor="start" x="1159.26" y="-488.74" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊤</text>
+<text text-anchor="start" x="1175.01" y="-488.74" font-family="Times New Roman,serif" font-size="14.00">:tuple</text>
+</g>
+<!-- TOP&#45;&gt;TUPLE_TOP -->
+<g id="edge56" class="edge">
+<title>TOP&#45;&gt;TUPLE_TOP</title>
+<path fill="none" stroke="black" d="M662.72,-551.08C740.91,-542.46 1014.51,-512.31 1130.21,-499.56"/>
+<polygon fill="black" stroke="black" points="1130.5,-503.05 1140.05,-498.47 1129.73,-496.09 1130.5,-503.05"/>
+</g>
+<!-- BOT -->
+<g id="node2" class="node">
+<title>BOT</title>
+<ellipse fill="black" stroke="black" cx="641.51" cy="-21.12" rx="21.12" ry="21.12"/>
+<text text-anchor="start" x="633.63" y="-16.7" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00" fill="white">⊥</text>
+</g>
+<!-- CTRL -->
+<g id="node4" class="node">
+<title>CTRL</title>
+<ellipse fill="yellow" stroke="black" cx="49.51" cy="-82.75" rx="36.51" ry="18"/>
+<text text-anchor="start" x="30.76" y="-78.7" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊥</text>
+<text text-anchor="start" x="46.51" y="-78.7" font-family="Times New Roman,serif" font-size="14.00">:ctrl</text>
+</g>
+<!-- XCTRL&#45;&gt;CTRL -->
+<g id="edge2" class="edge">
+<title>XCTRL&#45;&gt;CTRL</title>
+<path fill="none" stroke="black" d="M37.09,-474.38C39.15,-409.6 46.05,-191.88 48.57,-112.25"/>
+<polygon fill="black" stroke="black" points="52.06,-112.73 48.88,-102.63 45.06,-112.51 52.06,-112.73"/>
+</g>
+<!-- CTRL&#45;&gt;BOT -->
+<g id="edge3" class="edge">
+<title>CTRL&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M85.21,-78.15C191.74,-67.42 506.36,-35.74 608.84,-25.41"/>
+<polygon fill="black" stroke="black" points="609.15,-28.9 618.75,-24.42 608.45,-21.94 609.15,-28.9"/>
+</g>
+<!-- INT_HI -->
+<g id="node7" class="node">
+<title>INT_HI</title>
+<ellipse fill="lightblue" stroke="black" cx="174.51" cy="-434.29" rx="53.91" ry="18"/>
+<text text-anchor="middle" x="174.51" y="-429.24" font-family="Times New Roman,serif" font-size="14.00">[min&gt;max]</text>
+</g>
+<!-- INT_TOP&#45;&gt;INT_HI -->
+<g id="edge5" class="edge">
+<title>INT_TOP&#45;&gt;INT_HI</title>
+<path fill="none" stroke="black" d="M289.8,-481.17C269.89,-473.25 242.26,-462.25 219.03,-453.01"/>
+<polygon fill="black" stroke="black" points="220.37,-449.77 209.78,-449.33 217.78,-456.28 220.37,-449.77"/>
+</g>
+<!-- INT_BOT -->
+<g id="node6" class="node">
+<title>INT_BOT</title>
+<ellipse fill="lightblue" stroke="black" cx="329.51" cy="-82.75" rx="33.95" ry="18"/>
+<text text-anchor="start" x="312.63" y="-78.7" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊥</text>
+<text text-anchor="start" x="328.38" y="-78.7" font-family="Times New Roman,serif" font-size="14.00">:int</text>
+</g>
+<!-- INT_BOT&#45;&gt;BOT -->
+<g id="edge15" class="edge">
+<title>INT_BOT&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M361.14,-75.7C420.84,-64.3 549.47,-39.71 609.47,-28.25"/>
+<polygon fill="black" stroke="black" points="609.86,-31.73 619.03,-26.42 608.55,-24.86 609.86,-31.73"/>
+</g>
+<!-- INT_XBOOL -->
+<g id="node8" class="node">
+<title>INT_XBOOL</title>
+<ellipse fill="lightblue" stroke="black" cx="97.51" cy="-373.97" rx="33.95" ry="18"/>
+<text text-anchor="middle" x="97.51" y="-368.92" font-family="Times New Roman,serif" font-size="14.00">[1...0]</text>
+</g>
+<!-- INT_HI&#45;&gt;INT_XBOOL -->
+<g id="edge6" class="edge">
+<title>INT_HI&#45;&gt;INT_XBOOL</title>
+<path fill="none" stroke="black" d="M153.47,-417.36C144.79,-410.78 134.6,-403.06 125.31,-396.03"/>
+<polygon fill="black" stroke="black" points="127.71,-393.46 117.63,-390.21 123.48,-399.04 127.71,-393.46"/>
+</g>
+<!-- INT_CON -->
+<g id="node9" class="node">
+<title>INT_CON</title>
+<ellipse fill="lightblue" stroke="black" cx="174.51" cy="-282.65" rx="45.21" ry="18"/>
+<text text-anchor="middle" x="174.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">constants</text>
+</g>
+<!-- INT_HI&#45;&gt;INT_CON -->
+<g id="edge9" class="edge">
+<title>INT_HI&#45;&gt;INT_CON</title>
+<path fill="none" stroke="black" d="M174.51,-416C174.51,-390.27 174.51,-343.1 174.51,-312.31"/>
+<polygon fill="black" stroke="black" points="178.01,-312.52 174.51,-302.52 171.01,-312.52 178.01,-312.52"/>
+</g>
+<!-- INT_CON0 -->
+<g id="node10" class="node">
+<title>INT_CON0</title>
+<ellipse fill="lightblue" stroke="black" cx="47.51" cy="-282.65" rx="18" ry="18"/>
+<text text-anchor="middle" x="47.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">0</text>
+</g>
+<!-- INT_XBOOL&#45;&gt;INT_CON0 -->
+<g id="edge7" class="edge">
+<title>INT_XBOOL&#45;&gt;INT_CON0</title>
+<path fill="none" stroke="black" d="M88.34,-356.59C80.82,-343.17 70.07,-323.96 61.49,-308.62"/>
+<polygon fill="black" stroke="black" points="64.63,-307.08 56.69,-300.06 58.53,-310.5 64.63,-307.08"/>
+</g>
+<!-- INT_CON1 -->
+<g id="node11" class="node">
+<title>INT_CON1</title>
+<ellipse fill="lightblue" stroke="black" cx="97.51" cy="-282.65" rx="18" ry="18"/>
+<text text-anchor="middle" x="97.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">1</text>
+</g>
+<!-- INT_XBOOL&#45;&gt;INT_CON1 -->
+<g id="edge8" class="edge">
+<title>INT_XBOOL&#45;&gt;INT_CON1</title>
+<path fill="none" stroke="black" d="M97.51,-355.75C97.51,-343.47 97.51,-326.68 97.51,-312.39"/>
+<polygon fill="black" stroke="black" points="101.01,-312.64 97.51,-302.64 94.01,-312.64 101.01,-312.64"/>
+</g>
+<!-- INT_LO -->
+<g id="node13" class="node">
+<title>INT_LO</title>
+<ellipse fill="lightblue" stroke="black" cx="174.51" cy="-141.25" rx="53.91" ry="18"/>
+<text text-anchor="middle" x="174.51" y="-136.2" font-family="Times New Roman,serif" font-size="14.00">[min&lt;max]</text>
+</g>
+<!-- INT_CON&#45;&gt;INT_LO -->
+<g id="edge13" class="edge">
+<title>INT_CON&#45;&gt;INT_LO</title>
+<path fill="none" stroke="black" d="M174.51,-264.17C174.51,-240.45 174.51,-199.04 174.51,-170.9"/>
+<polygon fill="black" stroke="black" points="178.01,-171.25 174.51,-161.25 171.01,-171.25 178.01,-171.25"/>
+</g>
+<!-- INT_CON0&#45;&gt;INT_CON1 -->
+<!-- INT_BOOL -->
+<g id="node12" class="node">
+<title>INT_BOOL</title>
+<ellipse fill="lightblue" stroke="black" cx="97.51" cy="-196.45" rx="33.95" ry="18"/>
+<text text-anchor="middle" x="97.51" y="-191.4" font-family="Times New Roman,serif" font-size="14.00">[0...1]</text>
+</g>
+<!-- INT_CON0&#45;&gt;INT_BOOL -->
+<g id="edge10" class="edge">
+<title>INT_CON0&#45;&gt;INT_BOOL</title>
+<path fill="none" stroke="black" d="M56.45,-266.6C63.5,-254.72 73.51,-237.87 81.88,-223.77"/>
+<polygon fill="black" stroke="black" points="84.75,-225.79 86.85,-215.41 78.73,-222.22 84.75,-225.79"/>
+</g>
+<!-- INT_CON1&#45;&gt;INT_CON -->
+<!-- INT_CON1&#45;&gt;INT_BOOL -->
+<g id="edge11" class="edge">
+<title>INT_CON1&#45;&gt;INT_BOOL</title>
+<path fill="none" stroke="black" d="M97.51,-264.21C97.51,-253.25 97.51,-238.87 97.51,-226.25"/>
+<polygon fill="black" stroke="black" points="101.01,-226.39 97.51,-216.39 94.01,-226.39 101.01,-226.39"/>
+</g>
+<!-- INT_BOOL&#45;&gt;INT_LO -->
+<g id="edge12" class="edge">
+<title>INT_BOOL&#45;&gt;INT_LO</title>
+<path fill="none" stroke="black" d="M117.34,-181.75C124.98,-176.47 133.91,-170.3 142.42,-164.42"/>
+<polygon fill="black" stroke="black" points="144.27,-167.4 150.5,-158.83 140.29,-161.64 144.27,-167.4"/>
+</g>
+<!-- INT_LO&#45;&gt;INT_BOT -->
+<g id="edge14" class="edge">
+<title>INT_LO&#45;&gt;INT_BOT</title>
+<path fill="none" stroke="black" d="M210.07,-127.29C234.52,-118.37 266.93,-106.56 291.82,-97.49"/>
+<polygon fill="black" stroke="black" points="292.71,-100.89 300.91,-94.17 290.31,-94.31 292.71,-100.89"/>
+</g>
+<!-- FLT_CON64 -->
+<g id="node16" class="node">
+<title>FLT_CON64</title>
+<ellipse fill="aqua" stroke="black" cx="564.51" cy="-282.65" rx="55.33" ry="40.66"/>
+<text text-anchor="middle" x="564.51" y="-294.1" font-family="Times New Roman,serif" font-size="14.00">64b consts</text>
+<text text-anchor="middle" x="564.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">[excludes</text>
+<text text-anchor="middle" x="564.51" y="-261.1" font-family="Times New Roman,serif" font-size="14.00">32b consts]</text>
+</g>
+<!-- FLT_TOP&#45;&gt;FLT_CON64 -->
+<g id="edge19" class="edge">
+<title>FLT_TOP&#45;&gt;FLT_CON64</title>
+<path fill="none" stroke="black" d="M500.48,-474.88C510.8,-443.88 532.35,-379.2 547.59,-333.44"/>
+<polygon fill="black" stroke="black" points="550.9,-334.57 550.74,-323.98 544.26,-332.36 550.9,-334.57"/>
+</g>
+<!-- FLT_CONPI -->
+<g id="node18" class="node">
+<title>FLT_CONPI</title>
+<ellipse fill="aqua" stroke="black" cx="446.51" cy="-282.65" rx="48.79" ry="18"/>
+<text text-anchor="middle" x="446.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">3.14159...</text>
+</g>
+<!-- FLT_TOP&#45;&gt;FLT_CONPI -->
+<g id="edge20" class="edge">
+<title>FLT_TOP&#45;&gt;FLT_CONPI</title>
+<path fill="none" stroke="black" d="M490.33,-474.51C482.02,-438.11 463.32,-356.27 453.25,-312.16"/>
+<polygon fill="black" stroke="black" points="456.69,-311.49 451.05,-302.52 449.86,-313.04 456.69,-311.49"/>
+</g>
+<!-- FLT_X32 -->
+<g id="node19" class="node">
+<title>FLT_X32</title>
+<ellipse fill="aqua" stroke="black" cx="333.51" cy="-373.97" rx="28.32" ry="28.32"/>
+<text text-anchor="middle" x="333.51" y="-368.92" font-family="Times New Roman,serif" font-size="14.00">~f32</text>
+</g>
+<!-- FLT_TOP&#45;&gt;FLT_X32 -->
+<g id="edge23" class="edge">
+<title>FLT_TOP&#45;&gt;FLT_X32</title>
+<path fill="none" stroke="black" d="M474.77,-478.22C447.56,-458.14 398.22,-421.73 365.65,-397.69"/>
+<polygon fill="black" stroke="black" points="367.88,-394.99 357.75,-391.86 363.72,-400.62 367.88,-394.99"/>
+</g>
+<!-- FLT_BOT -->
+<g id="node15" class="node">
+<title>FLT_BOT</title>
+<ellipse fill="aqua" stroke="black" cx="507.51" cy="-82.75" rx="32.41" ry="18"/>
+<text text-anchor="start" x="491.76" y="-78.7" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊥</text>
+<text text-anchor="start" x="507.51" y="-78.7" font-family="Times New Roman,serif" font-size="14.00">:flt</text>
+</g>
+<!-- FLT_BOT&#45;&gt;BOT -->
+<g id="edge29" class="edge">
+<title>FLT_BOT&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M532.4,-70.67C554.98,-60.63 588.29,-45.81 612.16,-35.19"/>
+<polygon fill="black" stroke="black" points="613.29,-38.51 621,-31.25 610.44,-32.12 613.29,-38.51"/>
+</g>
+<!-- FLT_CON64&#45;&gt;FLT_BOT -->
+<g id="edge21" class="edge">
+<title>FLT_CON64&#45;&gt;FLT_BOT</title>
+<path fill="none" stroke="black" d="M553.11,-242.68C542.05,-203.88 525.53,-145.95 515.71,-111.5"/>
+<polygon fill="black" stroke="black" points="519.17,-110.89 513.06,-102.23 512.44,-112.81 519.17,-110.89"/>
+</g>
+<!-- FLT_CON32 -->
+<g id="node17" class="node">
+<title>FLT_CON32</title>
+<ellipse fill="aqua" stroke="black" cx="333.51" cy="-282.65" rx="50.33" ry="18"/>
+<text text-anchor="middle" x="333.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">32b consts</text>
+</g>
+<!-- FLT_CON32&#45;&gt;FLT_CONPI -->
+<!-- FLT_32 -->
+<g id="node21" class="node">
+<title>FLT_32</title>
+<ellipse fill="aqua" stroke="black" cx="333.51" cy="-196.45" rx="23.2" ry="23.2"/>
+<text text-anchor="middle" x="333.51" y="-191.4" font-family="Times New Roman,serif" font-size="14.00">f32</text>
+</g>
+<!-- FLT_CON32&#45;&gt;FLT_32 -->
+<g id="edge27" class="edge">
+<title>FLT_CON32&#45;&gt;FLT_32</title>
+<path fill="none" stroke="black" d="M333.51,-264.21C333.51,-254.7 333.51,-242.59 333.51,-231.31"/>
+<polygon fill="black" stroke="black" points="337.01,-231.51 333.51,-221.51 330.01,-231.51 337.01,-231.51"/>
+</g>
+<!-- FLT_CONPI&#45;&gt;FLT_BOT -->
+<g id="edge22" class="edge">
+<title>FLT_CONPI&#45;&gt;FLT_BOT</title>
+<path fill="none" stroke="black" d="M452.03,-264.56C462.62,-229.86 485.86,-153.69 498.65,-111.79"/>
+<polygon fill="black" stroke="black" points="501.94,-112.98 501.51,-102.39 495.25,-110.93 501.94,-112.98"/>
+</g>
+<!-- FLT_CONPI&#45;&gt;FLT_CON64 -->
+<!-- FLT_X32&#45;&gt;FLT_CON32 -->
+<g id="edge25" class="edge">
+<title>FLT_X32&#45;&gt;FLT_CON32</title>
+<path fill="none" stroke="black" d="M333.51,-345.2C333.51,-334.71 333.51,-322.76 333.51,-312.19"/>
+<polygon fill="black" stroke="black" points="337.01,-312.52 333.51,-302.52 330.01,-312.53 337.01,-312.52"/>
+</g>
+<!-- FLT_CON0 -->
+<g id="node20" class="node">
+<title>FLT_CON0</title>
+<ellipse fill="aqua" stroke="black" cx="251.51" cy="-282.65" rx="18.08" ry="18.08"/>
+<text text-anchor="middle" x="251.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">0.</text>
+</g>
+<!-- FLT_X32&#45;&gt;FLT_CON0 -->
+<g id="edge24" class="edge">
+<title>FLT_X32&#45;&gt;FLT_CON0</title>
+<path fill="none" stroke="black" d="M314.9,-352.7C301.83,-338.47 284.38,-319.46 271.1,-304.99"/>
+<polygon fill="black" stroke="black" points="273.81,-302.77 264.47,-297.77 268.65,-307.5 273.81,-302.77"/>
+</g>
+<!-- FLT_CON0&#45;&gt;FLT_CON32 -->
+<!-- FLT_CON0&#45;&gt;FLT_32 -->
+<g id="edge26" class="edge">
+<title>FLT_CON0&#45;&gt;FLT_32</title>
+<path fill="none" stroke="black" d="M263.96,-268.86C276.06,-256.44 294.74,-237.26 309.69,-221.91"/>
+<polygon fill="black" stroke="black" points="312.03,-224.53 316.5,-214.92 307.01,-219.64 312.03,-224.53"/>
+</g>
+<!-- FLT_32&#45;&gt;FLT_BOT -->
+<g id="edge28" class="edge">
+<title>FLT_32&#45;&gt;FLT_BOT</title>
+<path fill="none" stroke="black" d="M353.13,-183.63C383.19,-163.99 440.9,-126.28 476.61,-102.94"/>
+<polygon fill="black" stroke="black" points="478.34,-105.99 484.79,-97.59 474.51,-100.13 478.34,-105.99"/>
+</g>
+<!-- PTR0 -->
+<g id="node23" class="node">
+<title>PTR0</title>
+<polygon fill="none" stroke="none" points="668.51,-109.25 614.51,-109.25 614.51,-56.25 668.51,-56.25 668.51,-109.25"/>
+<polygon fill="green" stroke="none" points="623.51,-82.75 623.51,-105.25 659.51,-105.25 659.51,-82.75 623.51,-82.75"/>
+<polygon fill="none" stroke="black" points="623.51,-82.75 623.51,-105.25 659.51,-105.25 659.51,-82.75 623.51,-82.75"/>
+<text text-anchor="start" x="627.63" y="-88.95" font-family="Times New Roman,serif" font-size="14.00" fill="white">*ptr?</text>
+<polygon fill="lightgreen" stroke="none" points="623.51,-60.25 623.51,-82.75 659.51,-82.75 659.51,-60.25 623.51,-60.25"/>
+<polygon fill="none" stroke="black" points="623.51,-60.25 623.51,-82.75 659.51,-82.75 659.51,-60.25 623.51,-60.25"/>
+<text text-anchor="start" x="626.51" y="-66.45" font-family="Times New Roman,serif" font-size="14.00">struct</text>
+</g>
+<!-- PTR&#45;&gt;PTR0 -->
+<g id="edge34" class="edge">
+<title>PTR&#45;&gt;PTR0</title>
+<path fill="none" stroke="black" d="M641.51,-466.52C641.51,-396.01 641.51,-202.44 641.51,-120.34"/>
+<polygon fill="black" stroke="black" points="645.01,-120.58 641.51,-110.58 638.01,-120.58 645.01,-120.58"/>
+</g>
+<!-- PTR0&#45;&gt;BOT -->
+<g id="edge35" class="edge">
+<title>PTR0&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M641.51,-56.46C641.51,-55.58 641.51,-54.7 641.51,-53.81"/>
+<polygon fill="black" stroke="black" points="645.01,-53.9 641.51,-43.9 638.01,-53.9 645.01,-53.9"/>
+</g>
+<!-- STRUCT_S1 -->
+<g id="node26" class="node">
+<title>STRUCT_S1</title>
+<polygon fill="none" stroke="none" points="741.38,-300.65 663.63,-300.65 663.63,-264.65 741.38,-264.65 741.38,-300.65"/>
+<polygon fill="lightgreen" stroke="none" points="671.63,-273.4 671.63,-291.9 698.38,-291.9 698.38,-273.4 671.63,-273.4"/>
+<polygon fill="none" stroke="black" points="671.63,-273.4 671.63,-291.9 698.38,-291.9 698.38,-273.4 671.63,-273.4"/>
+<text text-anchor="start" x="672.63" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">field</text>
+<defs>
+<linearGradient id="l_0" gradientUnits="userSpaceOnUse" x1="703.51" y1="-289.19" x2="728.26" y2="-276.11" >
+<stop offset="0" style="stop-color:lightblue;stop-opacity:1.;"/>
+<stop offset="1" style="stop-color:green;stop-opacity:1.;"/>
+</linearGradient>
+</defs>
+<polygon fill="url(#l_0)" stroke="none" points="698.38,-273.4 698.38,-291.9 733.38,-291.9 733.38,-273.4 698.38,-273.4"/>
+<polygon fill="none" stroke="black" points="698.38,-273.4 698.38,-291.9 733.38,-291.9 733.38,-273.4 698.38,-273.4"/>
+<text text-anchor="start" x="699.38" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">int/ptr</text>
+</g>
+<!-- STRUCT_TOP&#45;&gt;STRUCT_S1 -->
+<g id="edge37" class="edge">
+<title>STRUCT_TOP&#45;&gt;STRUCT_S1</title>
+<path fill="none" stroke="black" d="M742.68,-474.51C735.02,-437.92 717.75,-355.45 708.55,-311.5"/>
+<polygon fill="black" stroke="black" points="712.02,-311 706.54,-301.93 705.17,-312.43 712.02,-311"/>
+</g>
+<!-- STRUCT_S2 -->
+<g id="node27" class="node">
+<title>STRUCT_S2</title>
+<polygon fill="none" stroke="none" points="841.38,-309.15 755.63,-309.15 755.63,-256.15 841.38,-256.15 841.38,-309.15"/>
+<polygon fill="lightgreen" stroke="none" points="763.63,-282.65 763.63,-305.15 794.38,-305.15 794.38,-282.65 763.63,-282.65"/>
+<polygon fill="none" stroke="black" points="763.63,-282.65 763.63,-305.15 794.38,-305.15 794.38,-282.65 763.63,-282.65"/>
+<text text-anchor="start" x="766.63" y="-288.85" font-family="Times New Roman,serif" font-size="14.00">field</text>
+<defs>
+<linearGradient id="l_1" gradientUnits="userSpaceOnUse" x1="800.1" y1="-301.86" x2="827.67" y2="-285.95" >
+<stop offset="0" style="stop-color:lightblue;stop-opacity:1.;"/>
+<stop offset="1" style="stop-color:green;stop-opacity:1.;"/>
+</linearGradient>
+</defs>
+<polygon fill="url(#l_1)" stroke="none" points="794.38,-282.65 794.38,-305.15 833.38,-305.15 833.38,-282.65 794.38,-282.65"/>
+<polygon fill="none" stroke="black" points="794.38,-282.65 794.38,-305.15 833.38,-305.15 833.38,-282.65 794.38,-282.65"/>
+<text text-anchor="start" x="797.38" y="-288.85" font-family="Times New Roman,serif" font-size="14.00">int/ptr</text>
+<polygon fill="lightgreen" stroke="none" points="763.63,-260.15 763.63,-282.65 794.38,-282.65 794.38,-260.15 763.63,-260.15"/>
+<polygon fill="none" stroke="black" points="763.63,-260.15 763.63,-282.65 794.38,-282.65 794.38,-260.15 763.63,-260.15"/>
+<text text-anchor="start" x="766.63" y="-266.35" font-family="Times New Roman,serif" font-size="14.00">field</text>
+<defs>
+<linearGradient id="l_2" gradientUnits="userSpaceOnUse" x1="800.1" y1="-279.36" x2="827.67" y2="-263.45" >
+<stop offset="0" style="stop-color:lightblue;stop-opacity:1.;"/>
+<stop offset="1" style="stop-color:green;stop-opacity:1.;"/>
+</linearGradient>
+</defs>
+<polygon fill="url(#l_2)" stroke="none" points="794.38,-260.15 794.38,-282.65 833.38,-282.65 833.38,-260.15 794.38,-260.15"/>
+<polygon fill="none" stroke="black" points="794.38,-260.15 794.38,-282.65 833.38,-282.65 833.38,-260.15 794.38,-260.15"/>
+<text text-anchor="start" x="797.38" y="-266.35" font-family="Times New Roman,serif" font-size="14.00">int/ptr</text>
+</g>
+<!-- STRUCT_TOP&#45;&gt;STRUCT_S2 -->
+<g id="edge38" class="edge">
+<title>STRUCT_TOP&#45;&gt;STRUCT_S2</title>
+<path fill="none" stroke="black" d="M751.03,-474.51C759.53,-440.16 778.05,-365.34 789.28,-319.95"/>
+<polygon fill="black" stroke="black" points="792.67,-320.83 791.67,-310.28 785.87,-319.15 792.67,-320.83"/>
+</g>
+<!-- STRUCT_SN -->
+<g id="node28" class="node">
+<title>STRUCT_SN</title>
+<polygon fill="none" stroke="none" points="941.38,-320.4 855.63,-320.4 855.63,-244.9 941.38,-244.9 941.38,-320.4"/>
+<polygon fill="lightgreen" stroke="none" points="863.63,-293.9 863.63,-316.4 894.38,-316.4 894.38,-293.9 863.63,-293.9"/>
+<polygon fill="none" stroke="black" points="863.63,-293.9 863.63,-316.4 894.38,-316.4 894.38,-293.9 863.63,-293.9"/>
+<text text-anchor="start" x="866.63" y="-300.1" font-family="Times New Roman,serif" font-size="14.00">field</text>
+<defs>
+<linearGradient id="l_3" gradientUnits="userSpaceOnUse" x1="900.1" y1="-313.11" x2="927.67" y2="-297.2" >
+<stop offset="0" style="stop-color:lightblue;stop-opacity:1.;"/>
+<stop offset="1" style="stop-color:green;stop-opacity:1.;"/>
+</linearGradient>
+</defs>
+<polygon fill="url(#l_3)" stroke="none" points="894.38,-293.9 894.38,-316.4 933.38,-316.4 933.38,-293.9 894.38,-293.9"/>
+<polygon fill="none" stroke="black" points="894.38,-293.9 894.38,-316.4 933.38,-316.4 933.38,-293.9 894.38,-293.9"/>
+<text text-anchor="start" x="897.38" y="-300.1" font-family="Times New Roman,serif" font-size="14.00">int/ptr</text>
+<polygon fill="lightgreen" stroke="none" points="863.63,-271.4 863.63,-293.9 894.38,-293.9 894.38,-271.4 863.63,-271.4"/>
+<polygon fill="none" stroke="black" points="863.63,-271.4 863.63,-293.9 894.38,-293.9 894.38,-271.4 863.63,-271.4"/>
+<text text-anchor="start" x="869.63" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">... &#160;</text>
+<defs>
+<linearGradient id="l_4" gradientUnits="userSpaceOnUse" x1="900.1" y1="-290.61" x2="927.67" y2="-274.7" >
+<stop offset="0" style="stop-color:lightblue;stop-opacity:1.;"/>
+<stop offset="1" style="stop-color:green;stop-opacity:1.;"/>
+</linearGradient>
+</defs>
+<polygon fill="url(#l_4)" stroke="none" points="894.38,-271.4 894.38,-293.9 933.38,-293.9 933.38,-271.4 894.38,-271.4"/>
+<polygon fill="none" stroke="black" points="894.38,-271.4 894.38,-293.9 933.38,-293.9 933.38,-271.4 894.38,-271.4"/>
+<text text-anchor="start" x="897.38" y="-277.6" font-family="Times New Roman,serif" font-size="14.00">int/ptr</text>
+<polygon fill="lightgreen" stroke="none" points="863.63,-248.9 863.63,-271.4 894.38,-271.4 894.38,-248.9 863.63,-248.9"/>
+<polygon fill="none" stroke="black" points="863.63,-248.9 863.63,-271.4 894.38,-271.4 894.38,-248.9 863.63,-248.9"/>
+<text text-anchor="start" x="866.63" y="-255.1" font-family="Times New Roman,serif" font-size="14.00">field</text>
+<defs>
+<linearGradient id="l_5" gradientUnits="userSpaceOnUse" x1="900.1" y1="-268.11" x2="927.67" y2="-252.2" >
+<stop offset="0" style="stop-color:lightblue;stop-opacity:1.;"/>
+<stop offset="1" style="stop-color:green;stop-opacity:1.;"/>
+</linearGradient>
+</defs>
+<polygon fill="url(#l_5)" stroke="none" points="894.38,-248.9 894.38,-271.4 933.38,-271.4 933.38,-248.9 894.38,-248.9"/>
+<polygon fill="none" stroke="black" points="894.38,-248.9 894.38,-271.4 933.38,-271.4 933.38,-248.9 894.38,-248.9"/>
+<text text-anchor="start" x="897.38" y="-255.1" font-family="Times New Roman,serif" font-size="14.00">int/ptr</text>
+</g>
+<!-- STRUCT_TOP&#45;&gt;STRUCT_SN -->
+<g id="edge39" class="edge">
+<title>STRUCT_TOP&#45;&gt;STRUCT_SN</title>
+<path fill="none" stroke="black" d="M759.21,-475.24C782.17,-443.49 831.3,-375.56 864.63,-329.48"/>
+<polygon fill="black" stroke="black" points="867.37,-331.67 870.4,-321.52 861.7,-327.57 867.37,-331.67"/>
+</g>
+<!-- STRUCT_BOT -->
+<g id="node25" class="node">
+<title>STRUCT_BOT</title>
+<ellipse fill="lightgreen" stroke="black" cx="751.51" cy="-82.75" rx="44.7" ry="18"/>
+<text text-anchor="start" x="726.76" y="-78.7" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊥</text>
+<text text-anchor="start" x="742.51" y="-78.7" font-family="Times New Roman,serif" font-size="14.00">:struct</text>
+</g>
+<!-- STRUCT_BOT&#45;&gt;BOT -->
+<g id="edge43" class="edge">
+<title>STRUCT_BOT&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M725.72,-67.77C709,-58.7 687.2,-46.89 669.97,-37.55"/>
+<polygon fill="black" stroke="black" points="671.71,-34.51 661.25,-32.82 668.37,-40.67 671.71,-34.51"/>
+</g>
+<!-- STRUCT_S1&#45;&gt;STRUCT_BOT -->
+<g id="edge40" class="edge">
+<title>STRUCT_S1&#45;&gt;STRUCT_BOT</title>
+<path fill="none" stroke="black" d="M706.86,-264.91C715.3,-230.49 733.97,-154.31 744.29,-112.19"/>
+<polygon fill="black" stroke="black" points="747.69,-113.04 746.67,-102.5 740.89,-111.37 747.69,-113.04"/>
+</g>
+<!-- STRUCT_S1&#45;&gt;STRUCT_S2 -->
+<!-- STRUCT_S2&#45;&gt;STRUCT_BOT -->
+<g id="edge41" class="edge">
+<title>STRUCT_S2&#45;&gt;STRUCT_BOT</title>
+<path fill="none" stroke="black" d="M792.36,-256.52C783.62,-219.3 767.61,-151.25 758.45,-112.26"/>
+<polygon fill="black" stroke="black" points="761.88,-111.57 756.18,-102.64 755.07,-113.17 761.88,-111.57"/>
+</g>
+<!-- STRUCT_S2&#45;&gt;STRUCT_SN -->
+<!-- STRUCT_SN&#45;&gt;STRUCT_BOT -->
+<g id="edge42" class="edge">
+<title>STRUCT_SN&#45;&gt;STRUCT_BOT</title>
+<path fill="none" stroke="black" d="M870.86,-245.05C841.74,-205.46 796.64,-144.13 771.03,-109.3"/>
+<polygon fill="black" stroke="black" points="773.99,-107.42 765.25,-101.44 768.36,-111.57 773.99,-107.42"/>
+</g>
+<!-- MEM_ALIAS1 -->
+<g id="node31" class="node">
+<title>MEM_ALIAS1</title>
+<ellipse fill="blue" stroke="black" cx="975.51" cy="-282.65" rx="20.13" ry="20.13"/>
+<text text-anchor="middle" x="975.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00" fill="white">#1</text>
+</g>
+<!-- MEM_TOP&#45;&gt;MEM_ALIAS1 -->
+<g id="edge47" class="edge">
+<title>MEM_TOP&#45;&gt;MEM_ALIAS1</title>
+<path fill="none" stroke="black" d="M996.51,-474.51C992.58,-438.66 983.84,-358.73 978.96,-314.18"/>
+<polygon fill="black" stroke="black" points="982.45,-313.94 977.89,-304.38 975.5,-314.7 982.45,-313.94"/>
+</g>
+<!-- MEM_ALIASDOTS -->
+<g id="node32" class="node">
+<title>MEM_ALIASDOTS</title>
+<ellipse fill="blue" stroke="black" cx="1036.51" cy="-282.65" rx="27" ry="18"/>
+<text text-anchor="middle" x="1036.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00" fill="white">...</text>
+</g>
+<!-- MEM_TOP&#45;&gt;MEM_ALIASDOTS -->
+<g id="edge48" class="edge">
+<title>MEM_TOP&#45;&gt;MEM_ALIASDOTS</title>
+<path fill="none" stroke="black" d="M1001.81,-474.51C1008.41,-438.02 1023.27,-355.86 1031.23,-311.83"/>
+<polygon fill="black" stroke="black" points="1034.63,-312.69 1032.97,-302.23 1027.74,-311.45 1034.63,-312.69"/>
+</g>
+<!-- MEM_ALIASN -->
+<g id="node33" class="node">
+<title>MEM_ALIASN</title>
+<ellipse fill="blue" stroke="black" cx="1097.51" cy="-282.65" rx="20.13" ry="20.13"/>
+<text text-anchor="middle" x="1097.51" y="-277.6" font-family="Times New Roman,serif" font-size="14.00" fill="white">#n</text>
+</g>
+<!-- MEM_TOP&#45;&gt;MEM_ALIASN -->
+<g id="edge49" class="edge">
+<title>MEM_TOP&#45;&gt;MEM_ALIASN</title>
+<path fill="none" stroke="black" d="M1006.95,-474.88C1024.11,-438.46 1063.18,-355.52 1083.95,-311.44"/>
+<polygon fill="black" stroke="black" points="1087.07,-313.03 1088.16,-302.49 1080.73,-310.05 1087.07,-313.03"/>
+</g>
+<!-- MEM_BOT -->
+<g id="node30" class="node">
+<title>MEM_BOT</title>
+<ellipse fill="blue" stroke="black" cx="998.51" cy="-82.75" rx="43.67" ry="18"/>
+<text text-anchor="start" x="974.51" y="-78.7" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00" fill="white">⊥</text>
+<text text-anchor="start" x="990.26" y="-78.7" font-family="Times New Roman,serif" font-size="14.00" fill="white">:mem</text>
+</g>
+<!-- MEM_BOT&#45;&gt;BOT -->
+<g id="edge53" class="edge">
+<title>MEM_BOT&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M958.6,-75.08C887.17,-63.15 738.86,-38.38 673.56,-27.48"/>
+<polygon fill="black" stroke="black" points="674.3,-24.05 663.86,-25.86 673.15,-30.96 674.3,-24.05"/>
+</g>
+<!-- MEM_ALIAS1&#45;&gt;MEM_BOT -->
+<g id="edge50" class="edge">
+<title>MEM_ALIAS1&#45;&gt;MEM_BOT</title>
+<path fill="none" stroke="black" d="M977.84,-262.38C981.92,-226.96 990.35,-153.62 995.09,-112.45"/>
+<polygon fill="black" stroke="black" points="998.57,-112.87 996.23,-102.53 991.61,-112.07 998.57,-112.87"/>
+</g>
+<!-- MEM_ALIAS1&#45;&gt;MEM_ALIASDOTS -->
+<!-- MEM_ALIASDOTS&#45;&gt;MEM_BOT -->
+<g id="edge51" class="edge">
+<title>MEM_ALIASDOTS&#45;&gt;MEM_BOT</title>
+<path fill="none" stroke="black" d="M1033.07,-264.56C1026.49,-229.93 1012.06,-154.01 1004.08,-112.06"/>
+<polygon fill="black" stroke="black" points="1007.56,-111.6 1002.25,-102.43 1000.68,-112.91 1007.56,-111.6"/>
+</g>
+<!-- MEM_ALIASDOTS&#45;&gt;MEM_ALIASN -->
+<!-- MEM_ALIASN&#45;&gt;MEM_BOT -->
+<g id="edge52" class="edge">
+<title>MEM_ALIASN&#45;&gt;MEM_BOT</title>
+<path fill="none" stroke="black" d="M1088.37,-264.2C1070.97,-229.07 1032.98,-152.35 1012.41,-110.82"/>
+<polygon fill="black" stroke="black" points="1015.58,-109.34 1008.01,-101.93 1009.31,-112.45 1015.58,-109.34"/>
+</g>
+<!-- TUPLE1 -->
+<g id="node36" class="node">
+<title>TUPLE1</title>
+<polygon fill="none" stroke="none" points="1185.51,-309.15 1131.51,-309.15 1131.51,-256.15 1185.51,-256.15 1185.51,-309.15"/>
+<polygon fill="pink" stroke="none" points="1139.76,-282.65 1139.76,-305.15 1177.26,-305.15 1177.26,-282.65 1139.76,-282.65"/>
+<polygon fill="none" stroke="black" points="1139.76,-282.65 1139.76,-305.15 1177.26,-305.15 1177.26,-282.65 1139.76,-282.65"/>
+<text text-anchor="start" x="1142.76" y="-288.85" font-family="Times New Roman,serif" font-size="14.00">Tuple</text>
+<polygon fill="black" stroke="none" points="1139.76,-260.15 1139.76,-282.65 1177.26,-282.65 1177.26,-260.15 1139.76,-260.15"/>
+<polygon fill="none" stroke="black" points="1139.76,-260.15 1139.76,-282.65 1177.26,-282.65 1177.26,-260.15 1139.76,-260.15"/>
+<text text-anchor="start" x="1146.88" y="-266.35" font-family="Times New Roman,serif" font-size="14.00" fill="white">type</text>
+</g>
+<!-- TUPLE_TOP&#45;&gt;TUPLE1 -->
+<g id="edge57" class="edge">
+<title>TUPLE_TOP&#45;&gt;TUPLE1</title>
+<path fill="none" stroke="black" d="M1180.42,-474.51C1176.51,-440.23 1167.99,-365.66 1162.8,-320.24"/>
+<polygon fill="black" stroke="black" points="1166.28,-319.86 1161.67,-310.32 1159.33,-320.65 1166.28,-319.86"/>
+</g>
+<!-- TUPLE2 -->
+<g id="node37" class="node">
+<title>TUPLE2</title>
+<polygon fill="none" stroke="none" points="1253.51,-320.4 1199.51,-320.4 1199.51,-244.9 1253.51,-244.9 1253.51,-320.4"/>
+<polygon fill="pink" stroke="none" points="1207.76,-293.9 1207.76,-316.4 1245.26,-316.4 1245.26,-293.9 1207.76,-293.9"/>
+<polygon fill="none" stroke="black" points="1207.76,-293.9 1207.76,-316.4 1245.26,-316.4 1245.26,-293.9 1207.76,-293.9"/>
+<text text-anchor="start" x="1210.76" y="-300.1" font-family="Times New Roman,serif" font-size="14.00">Tuple</text>
+<polygon fill="black" stroke="none" points="1207.76,-271.4 1207.76,-293.9 1245.26,-293.9 1245.26,-271.4 1207.76,-271.4"/>
+<polygon fill="none" stroke="black" points="1207.76,-271.4 1207.76,-293.9 1245.26,-293.9 1245.26,-271.4 1207.76,-271.4"/>
+<text text-anchor="start" x="1214.88" y="-277.6" font-family="Times New Roman,serif" font-size="14.00" fill="white">type</text>
+<polygon fill="black" stroke="none" points="1207.76,-248.9 1207.76,-271.4 1245.26,-271.4 1245.26,-248.9 1207.76,-248.9"/>
+<polygon fill="none" stroke="black" points="1207.76,-248.9 1207.76,-271.4 1245.26,-271.4 1245.26,-248.9 1207.76,-248.9"/>
+<text text-anchor="start" x="1214.88" y="-255.1" font-family="Times New Roman,serif" font-size="14.00" fill="white">type</text>
+</g>
+<!-- TUPLE_TOP&#45;&gt;TUPLE2 -->
+<g id="edge58" class="edge">
+<title>TUPLE_TOP&#45;&gt;TUPLE2</title>
+<path fill="none" stroke="black" d="M1186.34,-474.51C1192.95,-442.94 1206.72,-377.19 1216.28,-331.51"/>
+<polygon fill="black" stroke="black" points="1219.68,-332.35 1218.3,-321.85 1212.83,-330.92 1219.68,-332.35"/>
+</g>
+<!-- TUPLEN -->
+<g id="node38" class="node">
+<title>TUPLEN</title>
+<polygon fill="none" stroke="none" points="1321.51,-331.65 1267.51,-331.65 1267.51,-233.65 1321.51,-233.65 1321.51,-331.65"/>
+<polygon fill="pink" stroke="none" points="1275.76,-305.15 1275.76,-327.65 1313.26,-327.65 1313.26,-305.15 1275.76,-305.15"/>
+<polygon fill="none" stroke="black" points="1275.76,-305.15 1275.76,-327.65 1313.26,-327.65 1313.26,-305.15 1275.76,-305.15"/>
+<text text-anchor="start" x="1278.76" y="-311.35" font-family="Times New Roman,serif" font-size="14.00">Tuple</text>
+<polygon fill="black" stroke="none" points="1275.76,-282.65 1275.76,-305.15 1313.26,-305.15 1313.26,-282.65 1275.76,-282.65"/>
+<polygon fill="none" stroke="black" points="1275.76,-282.65 1275.76,-305.15 1313.26,-305.15 1313.26,-282.65 1275.76,-282.65"/>
+<text text-anchor="start" x="1282.88" y="-288.85" font-family="Times New Roman,serif" font-size="14.00" fill="white">type</text>
+<polygon fill="black" stroke="none" points="1275.76,-260.15 1275.76,-282.65 1313.26,-282.65 1313.26,-260.15 1275.76,-260.15"/>
+<polygon fill="none" stroke="black" points="1275.76,-260.15 1275.76,-282.65 1313.26,-282.65 1313.26,-260.15 1275.76,-260.15"/>
+<text text-anchor="start" x="1288.88" y="-266.35" font-family="Times New Roman,serif" font-size="14.00" fill="white">...</text>
+<polygon fill="black" stroke="none" points="1275.76,-237.65 1275.76,-260.15 1313.26,-260.15 1313.26,-237.65 1275.76,-237.65"/>
+<polygon fill="none" stroke="black" points="1275.76,-237.65 1275.76,-260.15 1313.26,-260.15 1313.26,-237.65 1275.76,-237.65"/>
+<text text-anchor="start" x="1282.88" y="-243.85" font-family="Times New Roman,serif" font-size="14.00" fill="white">type</text>
+</g>
+<!-- TUPLE_TOP&#45;&gt;TUPLEN -->
+<g id="edge59" class="edge">
+<title>TUPLE_TOP&#45;&gt;TUPLEN</title>
+<path fill="none" stroke="black" d="M1192.06,-474.88C1207.65,-445.62 1239.24,-386.36 1263.24,-341.32"/>
+<polygon fill="black" stroke="black" points="1266.22,-343.18 1267.83,-332.71 1260.04,-339.88 1266.22,-343.18"/>
+</g>
+<!-- TUPLE_BOT -->
+<g id="node35" class="node">
+<title>TUPLE_BOT</title>
+<ellipse fill="pink" stroke="black" cx="1192.51" cy="-82.75" rx="42.65" ry="18"/>
+<text text-anchor="start" x="1169.26" y="-78.7" font-family="Times New Roman,serif" font-weight="bold" font-size="14.00">⊥</text>
+<text text-anchor="start" x="1185.01" y="-78.7" font-family="Times New Roman,serif" font-size="14.00">:tuple</text>
+</g>
+<!-- TUPLE_BOT&#45;&gt;BOT -->
+<g id="edge63" class="edge">
+<title>TUPLE_BOT&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M1151.54,-77.32C1046.53,-65.95 769.32,-35.95 674.14,-25.65"/>
+<polygon fill="black" stroke="black" points="674.52,-22.18 664.2,-24.58 673.77,-29.14 674.52,-22.18"/>
+</g>
+<!-- TUPLE1&#45;&gt;TUPLE_BOT -->
+<g id="edge60" class="edge">
+<title>TUPLE1&#45;&gt;TUPLE_BOT</title>
+<path fill="none" stroke="black" d="M1162.95,-256.52C1169.28,-219.3 1180.86,-151.25 1187.49,-112.26"/>
+<polygon fill="black" stroke="black" points="1190.9,-113.1 1189.12,-102.66 1184,-111.93 1190.9,-113.1"/>
+</g>
+<!-- TUPLE2&#45;&gt;TUPLE_BOT -->
+<g id="edge61" class="edge">
+<title>TUPLE2&#45;&gt;TUPLE_BOT</title>
+<path fill="none" stroke="black" d="M1220.11,-245.05C1213.55,-206.44 1203.46,-147.16 1197.47,-111.94"/>
+<polygon fill="black" stroke="black" points="1200.99,-111.74 1195.86,-102.47 1194.09,-112.92 1200.99,-111.74"/>
+</g>
+<!-- TUPLEN&#45;&gt;TUPLE_BOT -->
+<g id="edge62" class="edge">
+<title>TUPLEN&#45;&gt;TUPLE_BOT</title>
+<path fill="none" stroke="black" d="M1269.56,-233.75C1249.85,-195.12 1223.04,-142.58 1206.8,-110.75"/>
+<polygon fill="black" stroke="black" points="1210.07,-109.46 1202.41,-102.15 1203.83,-112.65 1210.07,-109.46"/>
+</g>
+</g>
+</svg>
diff --git a/chapter18/docs/lattice2.gv b/chapter18/docs/lattice2.gv
new file mode 100644
index 00000000..6aa37fa0
--- /dev/null
+++ b/chapter18/docs/lattice2.gv
@@ -0,0 +1,85 @@
+digraph Lattice {
+    compound = true;
+    // Define nodes
+    splines=false;
+    node [shape=oval, style=filled];
+    nodesep=0.2;
+    ranksep=0.4;
+
+    TOP [label="~scalar\n+int+tmp+0", fillcolor=black, fontcolor=white, group=center];
+
+    // ------------------------
+    PTRHQ [label="~tmp\n+tmp+0", fillcolor=green, fontcolor=white, group=left];
+    TOP -> PTRHQ
+
+    VALH_ [label="~nscalar\n+int+tmp", fillcolor=white, group=center];
+    TOP -> VALH_
+
+    INTHQ [label="~int\n+int+0", fillcolor=lightblue, group=right];
+    TOP -> INTHQ
+
+    LEFTHI [label="junk", style=invis, group=junkleft]
+  
+
+    PTRHQ -> LEFTHI-> VALH_ -> INTHQ [style=invis];
+    { rank=same; PTRHQ; LEFTHI; VALH_; INTHQ }
+
+    // ------------------------
+    PTRH_ [label="~ntmp\n+tmp", fillcolor=green, fontcolor=white, group=left];
+    VALH_ -> PTRH_
+    PTRHQ -> PTRH_
+
+    INTH_ [label="~nint\n+int", fillcolor=lightblue, group=right];
+    VALH_ -> INTH_
+    INTHQ -> INTH_
+    { rank=same; PTRH_; INTH_ }
+
+    // ------------------------
+    NILX_ [label="~nil\n[int,tmp]+0", fillcolor=aqua, group=junkleft];
+    INTHQ -> NILX_
+    PTRHQ -> NILX_
+    
+    NIL__ [label="nil\n[+int+tmp],0", fillcolor=pink];
+    VALH_ -> NIL__;
+    
+    NILX_ -> NIL__  [style=invis];
+    { rank=same; NIL__; NILX_ }
+
+    // ------------------------
+    PTRL_ [label="ntmp\ntmp", fillcolor=green, fontcolor=white, group=left];
+    PTRH_ -> PTRL_
+
+    INTL_ [label="nint\nint", fillcolor=lightblue, group=right];
+    INTH_ -> INTL_
+    { rank=same; PTRL_; INTL_ }
+    
+    // ------------------------
+    PTRL0 [label="tmp\ntmp,0", fillcolor=green, fontcolor=white, group=left];
+    PTRL_ -> PTRL0
+    NIL__ -> PTRL0
+
+    VALL_ [label="nscalar\nint,tmp", fillcolor=white, group=center];
+    PTRL_ -> VALL_
+    INTL_ -> VALL_
+    NILX_ -> VALL_
+
+    INTL0 [label="int\nint,0", fillcolor=lightblue, group=right];
+    INTL_ -> INTL0
+    NIL__ -> INTL0
+
+    PTRL0 -> VALL_ -> INTL0 [style=invis];
+    { rank=same; PTRL0; VALL_; INTL0 }
+
+    // ------------------------
+    BOT [label="scalar\nint,tmp,0", fillcolor=black, fontcolor=white, group=center];
+    PTRL0 -> BOT
+    INTL0 -> BOT
+    VALL_ -> BOT
+
+    // ------------------------
+    // Verticle alignment
+    TOP -> VALH_ -> VALL_ -> BOT [style=invis];
+    PTRHQ -> PTRH_ -> PTRL_ -> PTRL0 [style=invis];
+    INTHQ -> INTH_ -> INTL_ -> INTL0 [style=invis];
+    LEFTHI -> NILX_ [style=invis]
+}
diff --git a/chapter18/docs/lattice2.svg b/chapter18/docs/lattice2.svg
new file mode 100644
index 00000000..857bca2d
--- /dev/null
+++ b/chapter18/docs/lattice2.svg
@@ -0,0 +1,260 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 12.2.0 (20241103.1931)
+ -->
+<!-- Title: Lattice Pages: 1 -->
+<svg width="478pt" height="501pt"
+ viewBox="0.00 0.00 477.96 500.90" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 496.9)">
+<title>Lattice</title>
+<polygon fill="white" stroke="none" points="-4,4 -4,-496.9 473.96,-496.9 473.96,4 -4,4"/>
+<!-- TOP -->
+<g id="node1" class="node">
+<title>TOP</title>
+<ellipse fill="black" stroke="black" cx="240.13" cy="-463.91" rx="59.04" ry="28.99"/>
+<text text-anchor="middle" x="240.13" y="-467.11" font-family="Times New Roman,serif" font-size="14.00" fill="white">~scalar</text>
+<text text-anchor="middle" x="240.13" y="-450.61" font-family="Times New Roman,serif" font-size="14.00" fill="white">+int+tmp+0</text>
+</g>
+<!-- PTRHQ -->
+<g id="node2" class="node">
+<title>PTRHQ</title>
+<ellipse fill="green" stroke="black" cx="43.13" cy="-376.92" rx="43.13" ry="28.99"/>
+<text text-anchor="middle" x="43.13" y="-380.12" font-family="Times New Roman,serif" font-size="14.00" fill="white">~tmp</text>
+<text text-anchor="middle" x="43.13" y="-363.62" font-family="Times New Roman,serif" font-size="14.00" fill="white">+tmp+0</text>
+</g>
+<!-- TOP&#45;&gt;PTRHQ -->
+<g id="edge1" class="edge">
+<title>TOP&#45;&gt;PTRHQ</title>
+<path fill="none" stroke="black" d="M196.41,-444.04C164.74,-430.38 121.99,-411.94 89.68,-398"/>
+<polygon fill="black" stroke="black" points="91.11,-394.81 80.55,-394.06 88.34,-401.24 91.11,-394.81"/>
+</g>
+<!-- VALH_ -->
+<g id="node3" class="node">
+<title>VALH_</title>
+<ellipse fill="white" stroke="black" cx="240.13" cy="-376.92" rx="48.44" ry="28.99"/>
+<text text-anchor="middle" x="240.13" y="-380.12" font-family="Times New Roman,serif" font-size="14.00">~nscalar</text>
+<text text-anchor="middle" x="240.13" y="-363.62" font-family="Times New Roman,serif" font-size="14.00">+int+tmp</text>
+</g>
+<!-- TOP&#45;&gt;VALH_ -->
+<g id="edge2" class="edge">
+<title>TOP&#45;&gt;VALH_</title>
+<path fill="none" stroke="black" d="M235.15,-434.61C234.93,-429.02 234.85,-423.06 234.9,-417.18"/>
+<polygon fill="black" stroke="black" points="238.39,-417.69 235.12,-407.61 231.39,-417.52 238.39,-417.69"/>
+</g>
+<!-- TOP&#45;&gt;VALH_ -->
+<!-- INTHQ -->
+<g id="node4" class="node">
+<title>INTHQ</title>
+<ellipse fill="lightblue" stroke="black" cx="432.13" cy="-376.92" rx="37.83" ry="28.99"/>
+<text text-anchor="middle" x="432.13" y="-380.12" font-family="Times New Roman,serif" font-size="14.00">~int</text>
+<text text-anchor="middle" x="432.13" y="-363.62" font-family="Times New Roman,serif" font-size="14.00">+int+0</text>
+</g>
+<!-- TOP&#45;&gt;INTHQ -->
+<g id="edge3" class="edge">
+<title>TOP&#45;&gt;INTHQ</title>
+<path fill="none" stroke="black" d="M283.22,-443.83C314.91,-429.81 357.78,-410.83 389.39,-396.84"/>
+<polygon fill="black" stroke="black" points="390.53,-400.16 398.26,-392.92 387.7,-393.76 390.53,-400.16"/>
+</g>
+<!-- LEFTHI -->
+<!-- PTRHQ&#45;&gt;LEFTHI -->
+<!-- PTRH_ -->
+<g id="node6" class="node">
+<title>PTRH_</title>
+<ellipse fill="green" stroke="black" cx="43.13" cy="-289.94" rx="36.77" ry="28.99"/>
+<text text-anchor="middle" x="43.13" y="-293.14" font-family="Times New Roman,serif" font-size="14.00" fill="white">~ntmp</text>
+<text text-anchor="middle" x="43.13" y="-276.64" font-family="Times New Roman,serif" font-size="14.00" fill="white">+tmp</text>
+</g>
+<!-- PTRHQ&#45;&gt;PTRH_ -->
+<g id="edge8" class="edge">
+<title>PTRHQ&#45;&gt;PTRH_</title>
+<path fill="none" stroke="black" d="M38.15,-347.62C37.93,-342.03 37.85,-336.07 37.9,-330.2"/>
+<polygon fill="black" stroke="black" points="41.39,-330.71 38.12,-320.63 34.39,-330.54 41.39,-330.71"/>
+</g>
+<!-- PTRHQ&#45;&gt;PTRH_ -->
+<!-- NILX_ -->
+<g id="node8" class="node">
+<title>NILX_</title>
+<ellipse fill="aqua" stroke="black" cx="150.13" cy="-289.94" rx="56.39" ry="28.99"/>
+<text text-anchor="middle" x="150.13" y="-293.14" font-family="Times New Roman,serif" font-size="14.00">~nil</text>
+<text text-anchor="middle" x="150.13" y="-276.64" font-family="Times New Roman,serif" font-size="14.00">[int,tmp]+0</text>
+</g>
+<!-- PTRHQ&#45;&gt;NILX_ -->
+<g id="edge12" class="edge">
+<title>PTRHQ&#45;&gt;NILX_</title>
+<path fill="none" stroke="black" d="M70.41,-354.26C82.91,-344.33 97.94,-332.4 111.56,-321.58"/>
+<polygon fill="black" stroke="black" points="113.43,-324.56 119.09,-315.6 109.08,-319.08 113.43,-324.56"/>
+</g>
+<!-- VALH_&#45;&gt;INTHQ -->
+<!-- VALH_&#45;&gt;PTRH_ -->
+<g id="edge7" class="edge">
+<title>VALH_&#45;&gt;PTRH_</title>
+<path fill="none" stroke="black" d="M201.21,-359.13C167.78,-344.71 119.68,-323.96 85.33,-309.14"/>
+<polygon fill="black" stroke="black" points="87.1,-306.09 76.53,-305.35 84.33,-312.52 87.1,-306.09"/>
+</g>
+<!-- INTH_ -->
+<g id="node7" class="node">
+<title>INTH_</title>
+<ellipse fill="lightblue" stroke="black" cx="432.13" cy="-289.94" rx="31.47" ry="28.99"/>
+<text text-anchor="middle" x="432.13" y="-293.14" font-family="Times New Roman,serif" font-size="14.00">~nint</text>
+<text text-anchor="middle" x="432.13" y="-276.64" font-family="Times New Roman,serif" font-size="14.00">+int</text>
+</g>
+<!-- VALH_&#45;&gt;INTH_ -->
+<g id="edge9" class="edge">
+<title>VALH_&#45;&gt;INTH_</title>
+<path fill="none" stroke="black" d="M278.53,-358.93C311.9,-344.16 360.02,-322.86 393.48,-308.05"/>
+<polygon fill="black" stroke="black" points="394.67,-311.35 402.4,-304.1 391.84,-304.95 394.67,-311.35"/>
+</g>
+<!-- NIL__ -->
+<g id="node9" class="node">
+<title>NIL__</title>
+<ellipse fill="pink" stroke="black" cx="324.13" cy="-289.94" rx="62.23" ry="28.99"/>
+<text text-anchor="middle" x="324.13" y="-293.14" font-family="Times New Roman,serif" font-size="14.00">nil</text>
+<text text-anchor="middle" x="324.13" y="-276.64" font-family="Times New Roman,serif" font-size="14.00">[+int+tmp],0</text>
+</g>
+<!-- VALH_&#45;&gt;NIL__ -->
+<g id="edge13" class="edge">
+<title>VALH_&#45;&gt;NIL__</title>
+<path fill="none" stroke="black" d="M264.43,-351.34C272.67,-343.01 282.01,-333.55 290.83,-324.64"/>
+<polygon fill="black" stroke="black" points="293.12,-327.3 297.66,-317.72 288.14,-322.38 293.12,-327.3"/>
+</g>
+<!-- VALL_ -->
+<g id="node13" class="node">
+<title>VALL_</title>
+<ellipse fill="white" stroke="black" cx="240.13" cy="-115.97" rx="39.42" ry="28.99"/>
+<text text-anchor="middle" x="240.13" y="-119.17" font-family="Times New Roman,serif" font-size="14.00">nscalar</text>
+<text text-anchor="middle" x="240.13" y="-102.67" font-family="Times New Roman,serif" font-size="14.00">int,tmp</text>
+</g>
+<!-- VALH_&#45;&gt;VALL_ -->
+<!-- INTHQ&#45;&gt;INTH_ -->
+<g id="edge10" class="edge">
+<title>INTHQ&#45;&gt;INTH_</title>
+<path fill="none" stroke="black" d="M427.17,-348.1C426.94,-342.37 426.85,-336.25 426.9,-330.21"/>
+<polygon fill="black" stroke="black" points="430.39,-330.42 427.13,-320.34 423.39,-330.26 430.39,-330.42"/>
+</g>
+<!-- INTHQ&#45;&gt;INTH_ -->
+<!-- INTHQ&#45;&gt;NILX_ -->
+<g id="edge11" class="edge">
+<title>INTHQ&#45;&gt;NILX_</title>
+<path fill="none" stroke="black" d="M396.99,-365.33C350,-351.17 266.03,-325.87 209.23,-308.75"/>
+<polygon fill="black" stroke="black" points="210.28,-305.41 199.69,-305.88 208.26,-312.11 210.28,-305.41"/>
+</g>
+<!-- LEFTHI&#45;&gt;VALH_ -->
+<!-- LEFTHI&#45;&gt;NILX_ -->
+<!-- PTRL_ -->
+<g id="node10" class="node">
+<title>PTRL_</title>
+<ellipse fill="green" stroke="black" cx="43.13" cy="-202.96" rx="31.47" ry="28.99"/>
+<text text-anchor="middle" x="43.13" y="-206.16" font-family="Times New Roman,serif" font-size="14.00" fill="white">ntmp</text>
+<text text-anchor="middle" x="43.13" y="-189.66" font-family="Times New Roman,serif" font-size="14.00" fill="white">tmp</text>
+</g>
+<!-- PTRH_&#45;&gt;PTRL_ -->
+<g id="edge15" class="edge">
+<title>PTRH_&#45;&gt;PTRL_</title>
+<path fill="none" stroke="black" d="M38.17,-261.11C37.94,-255.39 37.85,-249.26 37.9,-243.22"/>
+<polygon fill="black" stroke="black" points="41.39,-243.44 38.13,-233.36 34.39,-243.27 41.39,-243.44"/>
+</g>
+<!-- PTRH_&#45;&gt;PTRL_ -->
+<!-- INTL_ -->
+<g id="node11" class="node">
+<title>INTL_</title>
+<ellipse fill="lightblue" stroke="black" cx="432.13" cy="-202.96" rx="27" ry="28.99"/>
+<text text-anchor="middle" x="432.13" y="-206.16" font-family="Times New Roman,serif" font-size="14.00">nint</text>
+<text text-anchor="middle" x="432.13" y="-189.66" font-family="Times New Roman,serif" font-size="14.00">int</text>
+</g>
+<!-- INTH_&#45;&gt;INTL_ -->
+<g id="edge16" class="edge">
+<title>INTH_&#45;&gt;INTL_</title>
+<path fill="none" stroke="black" d="M427.17,-261.11C426.94,-255.39 426.85,-249.26 426.9,-243.22"/>
+<polygon fill="black" stroke="black" points="430.39,-243.44 427.13,-233.36 423.39,-243.27 430.39,-243.44"/>
+</g>
+<!-- INTH_&#45;&gt;INTL_ -->
+<!-- NILX_&#45;&gt;NIL__ -->
+<!-- NILX_&#45;&gt;VALL_ -->
+<g id="edge21" class="edge">
+<title>NILX_&#45;&gt;VALL_</title>
+<path fill="none" stroke="black" d="M164.79,-261.6C180.03,-232.15 203.95,-185.91 220.74,-153.45"/>
+<polygon fill="black" stroke="black" points="223.74,-155.27 225.23,-144.78 217.53,-152.06 223.74,-155.27"/>
+</g>
+<!-- PTRL0 -->
+<g id="node12" class="node">
+<title>PTRL0</title>
+<ellipse fill="green" stroke="black" cx="43.13" cy="-115.97" rx="34.12" ry="28.99"/>
+<text text-anchor="middle" x="43.13" y="-119.17" font-family="Times New Roman,serif" font-size="14.00" fill="white">tmp</text>
+<text text-anchor="middle" x="43.13" y="-102.67" font-family="Times New Roman,serif" font-size="14.00" fill="white">tmp,0</text>
+</g>
+<!-- NIL__&#45;&gt;PTRL0 -->
+<g id="edge18" class="edge">
+<title>NIL__&#45;&gt;PTRL0</title>
+<path fill="none" stroke="black" d="M286.24,-266.48C232.36,-233.13 134.24,-172.38 80.6,-139.17"/>
+<polygon fill="black" stroke="black" points="82.76,-136.39 72.41,-134.1 79.07,-142.34 82.76,-136.39"/>
+</g>
+<!-- INTL0 -->
+<g id="node14" class="node">
+<title>INTL0</title>
+<ellipse fill="lightblue" stroke="black" cx="432.13" cy="-115.97" rx="28.81" ry="28.99"/>
+<text text-anchor="middle" x="432.13" y="-119.17" font-family="Times New Roman,serif" font-size="14.00">int</text>
+<text text-anchor="middle" x="432.13" y="-102.67" font-family="Times New Roman,serif" font-size="14.00">int,0</text>
+</g>
+<!-- NIL__&#45;&gt;INTL0 -->
+<g id="edge23" class="edge">
+<title>NIL__&#45;&gt;INTL0</title>
+<path fill="none" stroke="black" d="M341.49,-261.99C360.34,-231.61 390.49,-183.05 410.79,-150.35"/>
+<polygon fill="black" stroke="black" points="413.65,-152.38 415.95,-142.04 407.7,-148.69 413.65,-152.38"/>
+</g>
+<!-- PTRL_&#45;&gt;PTRL0 -->
+<g id="edge17" class="edge">
+<title>PTRL_&#45;&gt;PTRL0</title>
+<path fill="none" stroke="black" d="M38.17,-174.13C37.94,-168.47 37.85,-162.41 37.9,-156.43"/>
+<polygon fill="black" stroke="black" points="41.39,-156.75 38.12,-146.67 34.39,-156.58 41.39,-156.75"/>
+</g>
+<!-- PTRL_&#45;&gt;PTRL0 -->
+<!-- PTRL_&#45;&gt;VALL_ -->
+<g id="edge19" class="edge">
+<title>PTRL_&#45;&gt;VALL_</title>
+<path fill="none" stroke="black" d="M71.36,-189.78C103.94,-175.73 157.92,-152.44 196.04,-135.99"/>
+<polygon fill="black" stroke="black" points="197.16,-139.32 204.96,-132.15 194.39,-132.9 197.16,-139.32"/>
+</g>
+<!-- INTL_&#45;&gt;VALL_ -->
+<g id="edge20" class="edge">
+<title>INTL_&#45;&gt;VALL_</title>
+<path fill="none" stroke="black" d="M407.43,-191.02C376.23,-177.21 322.01,-153.22 283.77,-136.29"/>
+<polygon fill="black" stroke="black" points="285.39,-133.18 274.83,-132.33 282.55,-139.58 285.39,-133.18"/>
+</g>
+<!-- INTL_&#45;&gt;INTL0 -->
+<g id="edge22" class="edge">
+<title>INTL_&#45;&gt;INTL0</title>
+<path fill="none" stroke="black" d="M427.17,-174.13C426.94,-168.41 426.85,-162.28 426.9,-156.24"/>
+<polygon fill="black" stroke="black" points="430.39,-156.46 427.13,-146.38 423.39,-156.29 430.39,-156.46"/>
+</g>
+<!-- INTL_&#45;&gt;INTL0 -->
+<!-- PTRL0&#45;&gt;VALL_ -->
+<!-- BOT -->
+<g id="node15" class="node">
+<title>BOT</title>
+<ellipse fill="black" stroke="black" cx="240.13" cy="-28.99" rx="46.85" ry="28.99"/>
+<text text-anchor="middle" x="240.13" y="-32.19" font-family="Times New Roman,serif" font-size="14.00" fill="white">scalar</text>
+<text text-anchor="middle" x="240.13" y="-15.69" font-family="Times New Roman,serif" font-size="14.00" fill="white">int,tmp,0</text>
+</g>
+<!-- PTRL0&#45;&gt;BOT -->
+<g id="edge26" class="edge">
+<title>PTRL0&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M73.48,-101.88C105.02,-88.28 154.83,-66.79 191.79,-50.85"/>
+<polygon fill="black" stroke="black" points="193.14,-54.08 200.94,-46.9 190.37,-47.65 193.14,-54.08"/>
+</g>
+<!-- VALL_&#45;&gt;INTL0 -->
+<!-- VALL_&#45;&gt;BOT -->
+<g id="edge28" class="edge">
+<title>VALL_&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M235.17,-87.15C234.94,-81.48 234.85,-75.42 234.9,-69.44"/>
+<polygon fill="black" stroke="black" points="238.39,-69.76 235.12,-59.68 231.39,-69.6 238.39,-69.76"/>
+</g>
+<!-- VALL_&#45;&gt;BOT -->
+<!-- INTL0&#45;&gt;BOT -->
+<g id="edge27" class="edge">
+<title>INTL0&#45;&gt;BOT</title>
+<path fill="none" stroke="black" d="M405.84,-103.34C375.52,-89.91 325.06,-67.58 287.78,-51.08"/>
+<polygon fill="black" stroke="black" points="289.59,-48.05 279.03,-47.21 286.75,-54.45 289.59,-48.05"/>
+</g>
+</g>
+</svg>
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/IterPeeps.java b/chapter18/src/main/java/com/seaofnodes/simple/IterPeeps.java
index c0b34263..aad9bf31 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/IterPeeps.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/IterPeeps.java
@@ -115,7 +115,7 @@ public abstract class IterPeeps {
         int old_cnt = Node.ITER_CNT, old_nop = Node.ITER_NOP_CNT;
         Node changed = stop.walk( n -> {
                 Node m = n;
-                if( n.compute().isa(n._type) && (!n.iskeep() || n._nid<=5) ) { // Types must be forwards, even if on worklist
+                if( n.compute().isa(n._type) && (!n.iskeep() || n._nid<=6) ) { // Types must be forwards, even if on worklist
                     if( WORK.on(n) ) return null;
                     m = n.peepholeOpt();
                     if( m==null ) return null;
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/JSViewer.java b/chapter18/src/main/java/com/seaofnodes/simple/JSViewer.java
index d208fc0c..7b8f2631 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/JSViewer.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/JSViewer.java
@@ -198,7 +198,7 @@ public class JSViewer implements AutoCloseable {
             if( level==0 && n!=null && n.nIns()>2 ) {
                 sb.i().p("<TR>");
                 for( int m=2; m<n.nIns(); m++ )
-                    cell(sb,"#"+m,n.in(m),"m"+m);
+                    cell(sb,"#"+m,n.alias(m),"m"+m);
                 sb.p("</TR>\n"); // End scope level
             }
             // Scope variables, empty if none
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
index 04af20f7..f7b7d0e9 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/Parser.java
@@ -24,6 +24,7 @@ public class Parser {
     public static StartNode START;
 
     public static ConstantNode ZERO; // Very common node, cached here
+    public static ConstantNode NIL;  // Very common node, cached here
     public static XCtrlNode XCTRL;   // Very common node, cached here
 
     // Next available memory alias number
@@ -110,7 +111,8 @@ public class Parser {
         _continueScope = _breakScope = null;
         START = new StartNode(arg);
         STOP = new StopNode(source);
-        ZERO = con(0).keep();
+        ZERO  = con(TypeInteger.ZERO).keep();
+        NIL  = con(Type.NIL).keep();
         XCTRL= new XCtrlNode().peephole().keep();
         ALIAS = 2; // alias 0 for the control, 1 for memory
         TYPES = defaultTypes();
@@ -124,9 +126,9 @@ public class Parser {
         return new HashMap<>() {{
             put("bool",TypeInteger.U1 );
             put("byte",TypeInteger.U8 );
-            put("f32" ,TypeFloat  .B32);
-            put("f64" ,TypeFloat  .BOT);
-            put("flt" ,TypeFloat  .BOT);
+            put("f32" ,TypeFloat  .F32);
+            put("f64" ,TypeFloat  .F64);
+            put("flt" ,TypeFloat  .F64);
             put("i16" ,TypeInteger.I16);
             put("i32" ,TypeInteger.I32);
             put("i64" ,TypeInteger.BOT);
@@ -170,7 +172,7 @@ public class Parser {
         for( StructNode init : INITS.values() )
             init.unkeep().kill();
         INITS.clear();
-        if (!_lexer.isEOF()) throw error("Syntax error, unexpected " + _lexer.getAnyNextToken());
+        if( !_lexer.isEOF() ) throw _errorSyntax("unexpected");
         STOP.peephole();
         JSViewer.show();
         if( show ) showGraph();
@@ -207,7 +209,6 @@ public class Parser {
     private Node parseStatement() {
         if( false ) return null;
         else if (matchx("return")  ) return parseReturn();
-        else if (match ("{")       ) return require(parseBlock(false),"}");
         else if (matchx("if")      ) return parseIf();
         else if (matchx("while")   ) return parseWhile();
         else if (matchx("for")     ) return parseFor();
@@ -216,6 +217,11 @@ public class Parser {
         else if (matchx("struct")  ) return parseStruct();
         else if (matchx("#showGraph")) return require(showGraph(),";");
         else if (matchx(";")       ) return null; // Empty statement
+        // Break ambiguity around leading function types and starting a block
+        else if (peek('{') && !isTypeFun() ) {
+            match("{");
+            return require(parseBlock(false),"}");
+        }
         // Declaration or normal assignment/expression
         else return parseDeclarationStatement();
     }
@@ -378,7 +384,7 @@ public class Parser {
         return toScope;
     }
 
-    private void checkLoopActive() { if (_breakScope == null) throw Parser.error("No active loop for a break or continue"); }
+    private void checkLoopActive() { if (_breakScope == null) throw error("No active loop for a break or continue"); }
 
     private Node parseContinue() { checkLoopActive(); return (_continueScope = require(jumpTo( _continueScope ),";"));  }
     private Node parseBreak   () {
@@ -602,13 +608,16 @@ public class Parser {
                 // var is always not-final, final if no Bang AND TMP since primitives are not-final by default
                 (t!=Type.BOTTOM && !hasBang && (t instanceof TypeMemPtr));
             // var/val, then type comes from expression
-            if( inferType )
+            if( inferType ) {
+                if( expr._type==Type.NIL )
+                    throw error("a not-null/non-zero expression");
                 t = expr._type.glb();
+            }
 
         } else {
             if( inferType && !_scope.inCon() )
                 throw errorSyntax("=expression");
-            expr = con(t.makeInit());
+            expr = t instanceof TypeMemPtr tn ? (tn._nil==3 ? NIL : con(Type.TOP)) : (t==Type.BOTTOM ? con(t) : ZERO);
         }
 
         // Lift expression, based on type
@@ -632,11 +641,11 @@ public class Parser {
      * @return The statement following the struct
      */
     private Node parseStruct() {
-        if (_xScopes.size() > 1) throw errorSyntax("struct declarations can only appear in top level scope");
+        if (_xScopes.size() > 1) throw error("struct declarations can only appear in top level scope");
         String typeName = requireId();
         Type t = TYPES.get(typeName);
         if( t!=null && !(t instanceof TypeMemPtr tmp && tmp.isFRef() ) )
-            throw errorSyntax("struct '" + typeName + "' cannot be redefined");
+            throw error("struct '" + typeName + "' cannot be redefined");
 
         // A Block scope parse, and inspect the scope afterward for fields.
         _scope.push(true);
@@ -655,7 +664,7 @@ public class Parser {
             fs[i-lexlen] = Field.make(v._name,v.type(),ALIAS++,v._final);
         }
         TypeStruct ts = s._ts = TypeStruct.make(typeName, fs);
-        TYPES.put(typeName, TypeMemPtr.make(ts));
+        TYPES.put(typeName, TypeMemPtr.make((byte)2,ts));
         INITS.put(typeName,s.peephole().keep());
         // Done with struct/block scope
         require("}");
@@ -673,23 +682,28 @@ public class Parser {
     // t = int|i8|i16|i32|i64|u8|u16|u32|u64|byte|bool | flt|f32|f64 | val | var | struct[?]
     private Type type() {
         int old1 = pos();
+        // Only type with a leading `{` is a function pointer...
+        if( peek('{') ) return typeFunPtr();
+
+        // Otherwise you get a type name
         String tname = _lexer.matchId();
         if( tname==null ) return null;
+
         // Convert the type name to a type.
         Type t0 = TYPES.get(tname);
         // No new types as keywords
         if( t0 == null && KEYWORDS.contains(tname) )
             return posT(old1);
-        Type t1 = t0 == null ? TypeMemPtr.make(TypeStruct.makeFRef(tname)) : t0; // Null: assume a forward ref type
+        if( t0 == Type.BOTTOM || t0 == Type.TOP ) return t0; // var/val type inference
+        Type t1 = t0 == null ? TypeMemPtr.make((byte)2,TypeStruct.makeFRef(tname)) :t0; // Null: assume a forward ref type
         // Nest arrays and '?' as needed
         Type t2 = t1;
         while( true ) {
-            assert !(t2 instanceof TypeStruct);
             if( match("?") ) {
                 if( !(t2 instanceof TypeMemPtr tmp) )
                     throw error("Type "+t0+" cannot be null");
-                if( tmp._nil ) throw error("Type "+t2+" already allows null");
-                t2 = TypeMemPtr.make(tmp._obj,true);
+                if( tmp._nil==3 ) throw error("Type "+t2+" already allows null");
+                t2 = tmp.makeFrom((byte)3);
             } else if( match("[]") ) {
                 t2 = typeAry(t2);
             } else
@@ -712,7 +726,7 @@ public class Parser {
 
     // Make an array type of t
     private TypeMemPtr typeAry( Type t ) {
-        if( t instanceof TypeMemPtr tmp && !tmp._nil )
+        if( t instanceof TypeMemPtr tmp && (tmp._nil==1|| tmp._nil==2)  )
             throw error("Arrays of reference types must always be nullable");
         String tname = "["+t.str()+"]";
         Type ta = TYPES.get(tname);
@@ -720,20 +734,44 @@ public class Parser {
         // Need make an array type.
         TypeStruct ts = TypeStruct.makeAry(TypeInteger.BOT,ALIAS++,t,ALIAS++);
         assert ts.str().equals(tname);
-        TypeMemPtr tary = TypeMemPtr.make(ts);
+        TypeMemPtr tary = TypeMemPtr.make((byte)2,ts);
         TYPES.put(tname,tary);
         return tary;
     }
 
-    // Fixup forward refs lazily.  Basically a Union-Find flavored read
-    // barrier.
-    Type lazyFRef(Type t) {
-        //if( !t.isFRef() ) return t;
-        //Type def = Parser.TYPES.get(((TypeMemPtr)t)._obj._name);
-        throw Utils.TODO();
+    // A function type is `{ type... -> type }` or `{ type }`.
+    private Type typeFunPtr() {
+        int old = pos();        // Record lexer position
+        match("{");             // Skip already-peeked '{'
+        Type t0 = type();       // Either return or first arg
+        if( t0==null ) return posT(old); // Not a function
+        if( match("}") )                 // No-arg function { -> type }
+            throw Utils.TODO();
+        Ary<Type> ts = new Ary<>(Type.class);
+        ts.push(null);          // Return filled in later
+        ts.push(t0);            // First argument
+        while( true ) {
+            if( match("->") ) { // End of arguments, parse return
+                Type ret = type();
+                if( ret==null ) return posT(old);
+                ts.set(0,ret);
+                if( !match("}") ) return posT(old); // Not a function
+                return TypeFunPtr.make(TypeTuple.make(ts.asAry()),match("?"));
+            }
+            Type t1 = type();
+            if( t1==null ) return posT(old); // Not a function
+            ts.push(t1);
+        }
 
     }
 
+    // True if a TypeFunPtr, without advancing parser
+    private boolean isTypeFun() {
+        int old = pos();
+        if( typeFunPtr()==null ) return false;
+        pos(old);
+        return true;
+    }
 
     /**
      * Parse an expression of the form:
@@ -908,7 +946,7 @@ public class Parser {
         if( _lexer.isNumber(_lexer.peek()) ) return parseLiteral();
         if( matchx("true" ) ) return con(1);
         if( matchx("false") ) return ZERO;
-        if( matchx("null" ) ) return con(TypeMemPtr.NULLPTR);
+        if( matchx("null" ) ) return NIL;
         if( match("(") ) return require(parseAsgn(), ")");
         if( matchx("new"  ) ) return alloc();
         // Expect an identifier now
@@ -1021,7 +1059,7 @@ public class Parser {
         // Initial values for every field
         for( int i = 0; i < len; i++ )
             ns[2+len+i] = init.get(i+idx);
-        Node nnn = new NewNode(TypeMemPtr.make(obj), ns).peephole();
+        Node nnn = new NewNode(TypeMemPtr.make((byte)2,obj), ns).peephole();
         for( int i = 0; i < len; i++ )
             memAlias(fs[i]._alias, new ProjNode(nnn,i+2,memName(fs[i]._alias)).peephole());
         return new ProjNode(nnn,1,obj._name).peephole();
@@ -1032,7 +1070,7 @@ public class Parser {
         int base = ary.aryBase ();
         int scale= ary.aryScale();
         Node size = peep(new AddNode(con(base),peep(new ShlNode(len.keep(),con(scale)))));
-        ALTMP.clear();  ALTMP.add(len.unkeep()); ALTMP.add(con(ary._fields[1]._type.makeInit()));
+        ALTMP.clear();  ALTMP.add(len.unkeep()); ALTMP.add(con(ary._fields[1]._type.makeZero()));
         return newStruct(ary,size,0,ALTMP);
     }
 
@@ -1061,10 +1099,6 @@ public class Parser {
         else if( match("[") ) name = "[]";
         else return expr;       // No postfix
 
-        // Sanity check expr for being a reference
-        if( !(expr._type instanceof TypeMemPtr ptr) )
-            throw error("Expected reference but got " + expr._type.str());
-
         // Happens when parsing known dead code, which often has other typing
         // issues.  Since the code is dead, possibly due to inlining, lets not
         // spoil the user experience with error messages.
@@ -1072,6 +1106,14 @@ public class Parser {
             // Exit out via parsing the trailing expression
             return matchOpx('=','=') ? parseAsgn() : parsePostfix(con(Type.TOP));
 
+        //
+        if( expr._type==Type.NIL )
+            throw error("Accessing unknown field '" + name + "' from 'null'");
+
+        // Sanity check expr for being a reference
+        if( !(expr._type instanceof TypeMemPtr ptr) )
+            throw error("Expected reference but got " + expr._type.str());
+
         // Sanity check field name for existing
         TypeMemPtr tmp = (TypeMemPtr)TYPES.get(ptr._obj._name);
         if( tmp == null ) throw error("Accessing unknown field '" + name + "' from '" + ptr + "'");
@@ -1162,7 +1204,7 @@ public class Parser {
      * </pre>
      */
     private ConstantNode parseLiteral() { return con(_lexer.parseNumber()); }
-    public static Node con( long con ) { return con(TypeInteger.constant(con));  }
+    public static Node con( long con ) { return con==0 ? ZERO : con(TypeInteger.constant(con));  }
     public static ConstantNode con( Type t ) { return (ConstantNode)new ConstantNode(t).peephole();  }
     public Node peep( Node n ) {
         // Peephole, then improve with lexically scoped guards
@@ -1212,13 +1254,11 @@ public class Parser {
         throw errorSyntax(syntax);
     }
 
-    RuntimeException errorSyntax(String syntax) {
-        return error("Syntax error, expected " + syntax + ": " + _lexer.getAnyNextToken());
-    }
-
-    public static RuntimeException error( String errorMessage ) {
-        return new RuntimeException(errorMessage);
+    RuntimeException errorSyntax(String syntax) { return _errorSyntax("expected "+syntax);  }
+    private RuntimeException _errorSyntax(String msg) {
+        return _lexer.error("Syntax error, "+msg+": " + _lexer.getAnyNextToken());
     }
+    RuntimeException error(String msg) { return _lexer.error(msg); }
 
     ////////////////////////////////////
     // Lexer components
@@ -1230,6 +1270,11 @@ public class Parser {
         // Tracks current position in input buffer
         private int _position = 0;
 
+        //
+        private int _line_number = 1;
+        // Start of current line
+        private int _line_start = 0;
+
         /**
          * Record the source text for lexing
          */
@@ -1263,9 +1308,16 @@ public class Parser {
         // Just crash if misused
         public byte peek(int off) { return _input[_position+off]; }
 
+        private void inc() {
+            if( _position++ < _input.length && _input[_position-1] == '\n' ) {
+                _line_number++;
+                _line_start = _position;
+            }
+        }
+        // Does not honor LF, so caller must roll back position on a LF
         private char nextChar() {
             char ch = peek();
-            _position++;
+            inc();
             return ch;
         }
 
@@ -1279,13 +1331,13 @@ public class Parser {
          */
         private void skipWhiteSpace() {
             while( true ) {
-                if( isWhiteSpace() ) _position++;
+                if( isWhiteSpace() ) inc();
                 // Skip // to end of line
                 else if( _position+2 < _input.length &&
                          _input[_position  ] == '/' &&
                          _input[_position+1] == '/') {
-                    _position += 2;
-                    while( !isEOF() && _input[_position] != '\n' ) _position++;
+                    inc(); inc();
+                    while( !isEOF() && _input[_position] != '\n' ) inc();
                 } else break;
             }
         }
@@ -1297,6 +1349,7 @@ public class Parser {
         // then advance the cursor past syntax.
         // Return false otherwise, and do not advance the cursor.
         boolean match(String syntax) {
+            assert syntax.indexOf('\n')==-1; // No newlines in match
             skipWhiteSpace();
             int len = syntax.length();
             if (_position + len > _input.length) return false;
@@ -1319,7 +1372,7 @@ public class Parser {
             skipWhiteSpace();
             if( _position+1 >= _input.length || _input[_position]!=c0 || _input[_position+1]==c1 )
                 return false;
-            _position++;
+            inc();
             return true;
         }
 
@@ -1357,7 +1410,8 @@ public class Parser {
             if( len > 0 ) {
                 if( len > 1 && _input[old]=='0' )
                     throw error("Syntax error: integer values cannot start with '0'");
-                return TypeInteger.constant(Long.parseLong(new String(_input,old,len)));
+                long i = Long.parseLong(new String(_input,old,len));
+                return TypeInteger.constant(i);
             }
             return TypeFloat.constant(Double.parseDouble(new String(_input,old,-len)));
         }
@@ -1419,5 +1473,11 @@ public class Parser {
             if( ch0 == '-' && ch1 == '-' ) { _position += 2; return (char)-1; }
             return 0;
         }
+
+        public RuntimeException error( String errorMessage ) {
+            // file:line:charoff err
+            //String msg = "src:"+_line_number+":"+(_position-_line_start)+" "+errorMessage;
+            return new RuntimeException(errorMessage);
+        }
     }
 }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/AddNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/AddNode.java
index 0834a381..e6704ea6 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/AddNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/AddNode.java
@@ -48,7 +48,7 @@ public class AddNode extends Node {
 
         // Add of 0.  We do not check for (0+x) because this will already
         // canonicalize to (x+0)
-        if( t2 instanceof TypeInteger i && i.isConstant() && i.value()==0 )
+        if( t2 == TypeInteger.ZERO )
             return lhs;
 
         // Add of same to a multiply by 2
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/BoolNode.java
index 7126806d..bf8f7455 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/BoolNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/BoolNode.java
@@ -2,10 +2,7 @@ package com.seaofnodes.simple.node;
 
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.Utils;
-import com.seaofnodes.simple.type.Type;
-import com.seaofnodes.simple.type.TypeInteger;
-import com.seaofnodes.simple.type.TypeFloat;
-import com.seaofnodes.simple.type.TypeMemPtr;
+import com.seaofnodes.simple.type.*;
 
 import java.util.BitSet;
 import static com.seaofnodes.simple.type.TypeInteger.*;
@@ -35,6 +32,10 @@ abstract public class BoolNode extends Node {
     public TypeInteger compute() {
         Type t1 = in(1)._type;
         Type t2 = in(2)._type;
+        // Exactly equals?
+        if( in(1)==in(2) )
+            // LT fails, both EQ and LE succeed
+            return this instanceof LT ? TypeInteger.FALSE : TypeInteger.TRUE;
         if( t1.isHigh() || t2.isHigh() )
             return BOOL.dual();
         if( t1 instanceof TypeInteger i1 &&
@@ -43,7 +44,7 @@ abstract public class BoolNode extends Node {
         if( t1 instanceof TypeFloat f1 &&
             t2 instanceof TypeFloat f2 &&
             f1.isConstant() && f2.isConstant() )
-            return TypeInteger.constant(doOp(f1.value(), f2.value()) ? 1 : 0);
+            return doOp(f1.value(), f2.value()) ? TypeInteger.TRUE : TypeInteger.FALSE;
         return BOOL;
     }
 
@@ -55,7 +56,7 @@ abstract public class BoolNode extends Node {
     public Node idealize() {
         // Compare of same
         if( in(1)==in(2) )
-            return new ConstantNode(doOp(ZERO,ZERO));
+            return this instanceof LT ? Parser.ZERO : new ConstantNode(TypeInteger.TRUE);
 
         // Equals pushes constant to the right; 5==X becomes X==5.
         if( this instanceof EQ ) {
@@ -66,7 +67,7 @@ abstract public class BoolNode extends Node {
                     return in(1)._type instanceof TypeFloat ? new EQF(in(2),in(1)) : new EQ(in(2),in(1));
             }
             // Equals X==0 becomes a !X
-            if( (in(2)._type == ZERO || in(2)._type == TypeMemPtr.NULLPTR) )
+            if( (in(2)._type == ZERO || in(2)._type == Type.NIL) )
                 return new NotNode(in(1));
         }
 
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/DivNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/DivNode.java
index 76e98678..0d5ed297 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/DivNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/DivNode.java
@@ -2,7 +2,6 @@ package com.seaofnodes.simple.node;
 
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-
 import java.util.BitSet;
 
 public class DivNode extends Node {
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/IfNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/IfNode.java
index 513b4721..dcd2d4c7 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/IfNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/IfNode.java
@@ -1,9 +1,7 @@
 package com.seaofnodes.simple.node;
 
 import com.seaofnodes.simple.IterPeeps;
-import com.seaofnodes.simple.type.Type;
-import com.seaofnodes.simple.type.TypeInteger;
-import com.seaofnodes.simple.type.TypeTuple;
+import com.seaofnodes.simple.type.*;
 import java.util.BitSet;
 import java.util.HashSet;
 
@@ -37,14 +35,14 @@ public class IfNode extends CFGNode implements MultiNode {
         Type t = pred._type;
         // High types mean NEITHER side is reachable.
         // Wait until the type falls to decide which way to go.
-        if( t == Type.TOP || t == TypeInteger.TOP )
+        if( t.isHigh() )
             return TypeTuple.IF_NEITHER;
         // If constant is 0 then false branch is reachable
         // Else true branch is reachable
         if( t.isConstant() )
-            return t.makeInit()==t ? TypeTuple.IF_FALSE : TypeTuple.IF_TRUE;
-        // Integers allow non-zero ranges: "1-65535"
-        if( t.makeZero().meet(t) != t )
+            return (t==Type.NIL || t==TypeInteger.ZERO) ? TypeTuple.IF_FALSE : TypeTuple.IF_TRUE;
+        // If adding a zero makes a difference, the predicate must not have a zero/null
+        if( !t.makeZero().isa(t) )
             return TypeTuple.IF_TRUE;
 
         return TypeTuple.IF_BOTH;
@@ -57,7 +55,7 @@ public class IfNode extends CFGNode implements MultiNode {
         if( !pred()._type.isHighOrConst() )
             for( CFGNode dom = idom(), prior=this; dom!=null;  prior = dom, dom = dom.idom() )
                 if( dom.addDep(this) instanceof IfNode iff && iff.pred().addDep(this)==pred() && prior instanceof CProjNode prj ) {
-                    setDef(1,new ConstantNode(TypeInteger.make(true,prj._idx==0?1:0)).peephole());
+                    setDef(1,new ConstantNode(TypeInteger.constant(prj._idx==0?1:0)).peephole());
                     return this;
                 }
         return null;
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/MemOpNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
index 82aab8ac..818d6352 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
@@ -1,5 +1,6 @@
 package com.seaofnodes.simple.node;
 
+import com.seaofnodes.simple.Utils;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeMemPtr;
 
@@ -48,7 +49,7 @@ public abstract class MemOpNode extends Node {
         // Already an error, but better error messages come from elsewhere
         if( ptr == Type.BOTTOM ) return null;
         // Better be a not-nil TMP
-        if( ptr instanceof TypeMemPtr tmp && !tmp._nil )
+        if( ptr instanceof TypeMemPtr tmp && tmp._nil==2 )
             return null;
         return "Might be null accessing '" + _name + "'";
     }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/MinusFNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/MinusFNode.java
index 9727f58b..2b749ba3 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/MinusFNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/MinusFNode.java
@@ -22,7 +22,7 @@ public class MinusFNode extends Node {
     public Type compute() {
         if (in(1)._type instanceof TypeFloat i0)
             return i0.isConstant() ? TypeFloat.constant(-i0.value()) : i0;
-        return TypeFloat.BOT;
+        return TypeFloat.F64;
     }
 
     @Override
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/MinusNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/MinusNode.java
index 760a4274..dd2cbd26 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/MinusNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/MinusNode.java
@@ -21,13 +21,11 @@ public class MinusNode extends Node {
 
     @Override
     public Type compute() {
-        if( in(1)._type instanceof TypeInteger i0 ) {
-            if( i0.isHigh() ) return TypeInteger.TOP;
-            if( i0==TypeInteger.BOT || i0._min == Long.MIN_VALUE || i0._max == Long.MIN_VALUE )
-                return TypeInteger.BOT;
+        if( in(1)._type.isHigh() ) return TypeInteger.TOP;
+        if( in(1)._type instanceof TypeInteger i0 &&
+            !(i0==TypeInteger.BOT || i0._min == Long.MIN_VALUE || i0._max == Long.MIN_VALUE) )
             return TypeInteger.make(-i0._max,-i0._min);
-        }
-        return TypeInteger.TOP.meet(in(1)._type);
+        return TypeInteger.BOT;
     }
 
     @Override
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/NewNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/NewNode.java
index ddb1e09a..54defe13 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/NewNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/NewNode.java
@@ -17,15 +17,16 @@ public class NewNode extends Node implements MultiNode {
 
     public NewNode(TypeMemPtr ptr, Node... nodes) {
         super(nodes);
+        assert ptr._nil!=3;
         _ptr = ptr;
         _len = ptr._obj._fields.length;
         // Control in slot 0
         assert nodes[0]._type==Type.CONTROL || nodes[0]._type == Type.XCONTROL;
         // Malloc-length in slot 1
-        assert nodes[1]._type instanceof TypeInteger;
+        assert nodes[1]._type instanceof TypeInteger || nodes[1]._type==Type.NIL;
         for( int i=0; i<_len; i++ ) {
             // Memory slices for all fields.
-            assert nodes[2+     i]._type instanceof TypeMem;
+            assert nodes[2+     i]._type.isa(TypeMem.BOT);
             // Value  slices for all fields.
             assert nodes[2 + _len + i]._type != null;
         }
@@ -57,7 +58,8 @@ public class NewNode extends Node implements MultiNode {
         ts[0] = Type.CONTROL;
         ts[1] = _ptr;
         for( int i=0; i<fs.length; i++ ) {
-            TypeMem mem = (TypeMem)in(i+2)._type;
+            Type mt = in(i+2)._type;
+            TypeMem mem = mt==Type.TOP ? TypeMem.TOP : (TypeMem)in(i+2)._type;
             Type tfld = in(2+_len+i)._type.meet(mem._t);
             ts[i+2] = TypeMem.make(fs[i]._alias,tfld);
         }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter18/src/main/java/com/seaofnodes/simple/node/Node.java
index e23a128a..1a595f49 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -359,8 +359,9 @@ public abstract class Node implements OutNode {
         if( n != null )         // Something changed
             return n;           // Report progress
 
-        if( old==_type ) ITER_NOP_CNT++;
-        return old==_type ? null : this; // Report progress
+        if( old!=_type ) return this; // Report progress;
+        ITER_NOP_CNT++;
+        return null;            // No progress
     }
     public static int ITER_CNT, ITER_NOP_CNT;
 
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/NotNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/NotNode.java
index 664d7c7b..d71e0fe6 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/NotNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/NotNode.java
@@ -18,25 +18,13 @@ public class NotNode extends Node {
     }
 
     @Override
-    public Type compute() {
+    public TypeInteger compute() {
         Type t0 = in(1)._type;
-        if( t0.isHigh() ) return TypeInteger.BOOL.dual();
-        switch( t0 ) {
-        case TypeInteger i0:  return i0._max < 0 || i0._min > 0 ? TypeInteger.FALSE : (i0==TypeInteger.ZERO ? TypeInteger.TRUE : TypeInteger.BOOL);
-        case TypeFloat   i0:  return i0.isConstant() ? TypeInteger.constant(i0.value()==0 ? 1 : 0) : i0;
-        case TypeMemPtr p0:
-            // top->top, bot->bot, null->1, *void->0, not-null ptr->0, ptr/nil->bot
-            // If input in null then true
-            // If input is not null ptr then false
-            if( p0 == TypeMemPtr.NULLPTR ) return TypeInteger.TRUE;
-            if( !p0._nil )                 return TypeInteger.FALSE;
-            return TypeInteger.BOOL;
-        case Type t:
-            if( t0.getClass() != Type.class )
-                // Only doing NOT on ints and ptrs
-                throw Utils.TODO();
-            return TypeInteger.BOOL;
-        }
+        if( t0.isHigh() )  return TypeInteger.BOOL.dual();
+        if( t0 == Type.NIL || t0 == TypeInteger.ZERO ) return TypeInteger.TRUE;
+        if( t0 instanceof TypeNil tn && tn._nil==2 ) return TypeInteger.FALSE;
+        if( t0 instanceof TypeInteger i && (i._min > 0 || i._max < 0) ) return TypeInteger.FALSE;
+        return TypeInteger.BOOL;
     }
 
     @Override
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/PhiNode.java
index 407cf378..c0557639 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/PhiNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -1,9 +1,9 @@
 package com.seaofnodes.simple.node;
 
+import com.seaofnodes.simple.Utils;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeMem;
-import com.seaofnodes.simple.Utils;
-
+import com.seaofnodes.simple.type.TypeNil;
 import java.util.BitSet;
 
 public class PhiNode extends Node {
@@ -47,7 +47,7 @@ public class PhiNode extends Node {
         // During parsing Phis have to be computed type pessimistically.
         if( r.inProgress() ) return _declaredType;
         // Set type to local top of the starting type
-        Type t = _declaredType.lub();
+        Type t = Type.TOP;
         for (int i = 1; i < nIns(); i++)
             // If the region's control input is live, add this as a dependency
             // to the control because we can be peeped should it become dead.
@@ -101,10 +101,12 @@ public class PhiNode extends Node {
         // then replace with plain val.
         if( nIns()==3 ) {
             int nullx = -1;
-            if( in(1)._type == in(1)._type.makeInit() ) nullx = 1;
-            if( in(2)._type == in(2)._type.makeInit() ) nullx = 2;
+            if( in(1)._type == in(1)._type.makeZero() ) nullx = 1;
+            if( in(2)._type == in(2)._type.makeZero() ) nullx = 2;
             if( nullx != -1 ) {
                 Node val = in(3-nullx);
+                if( val instanceof CastNode cast )
+                    val = cast.in(1);
                 if( r.idom(this).addDep(this) instanceof IfNode iff && iff.pred().addDep(this)==val ) {
                     // Must walk the idom on the null side to make sure we hit False.
                     CFGNode idom = (CFGNode)r.in(nullx);
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java b/chapter18/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java
index 44d3a587..8311405d 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java
@@ -30,7 +30,7 @@ public class RoundF32Node extends Node {
         Type t1 = lhs._type;
 
         // RoundF32 of float
-        if( t1 instanceof TypeFloat tf && tf._sz==32 )
+        if( t1 instanceof TypeFloat tf && tf._f32 )
             return lhs;
 
         return null;
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/SarNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/SarNode.java
index 59cec99c..4270ef88 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/SarNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/SarNode.java
@@ -2,7 +2,6 @@ package com.seaofnodes.simple.node;
 
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-
 import java.util.BitSet;
 
 public class SarNode extends Node {
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java
index f69461cc..e9a4eb82 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java
@@ -70,7 +70,7 @@ public class ScopeMinNode extends Node {
 
     public Node in( Var v ) { return in(v._idx); }
 
-    Node alias( int alias ) {
+    public Node alias( int alias ) {
         return in(alias<nIns() && in(alias)!=null ? alias : 1);
     }
 
@@ -114,7 +114,7 @@ public class ScopeMinNode extends Node {
                 //Var v = _vars.at(i);
                 Node lhs = this._mem(i,null);
                 Node rhs = that._mem(i,null);
-                alias(i, new PhiNode(Parser.memName(i), TypeMem.BOT, r, lhs, rhs).peephole());
+                alias(i, new PhiNode(Parser.memName(i), lhs._type.glb().meet(rhs._type.glb()), r, lhs, rhs).peephole());
             }
     }
 
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
index 0d8ad2fc..e720a58f 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -1,8 +1,6 @@
 package com.seaofnodes.simple.node;
 
-import com.seaofnodes.simple.Ary;
-import com.seaofnodes.simple.IterPeeps;
-import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.*;
 import com.seaofnodes.simple.type.*;
 import java.util.*;
 import static com.seaofnodes.simple.Utils.TODO;
@@ -230,7 +228,7 @@ public class ScopeNode extends ScopeMinNode {
      * @return A new node representing the merge point
      */
     public RegionNode mergeScopes(ScopeNode that) {
-        RegionNode r = (RegionNode) ctrl(new RegionNode(null,ctrl(), that.ctrl()).keep());
+        RegionNode r = ctrl(new RegionNode(null,ctrl(), that.ctrl()).keep());
         mem()._merge(that.mem(),r);
         this ._merge(that      ,r);
         that.kill();            // Kill merged scope
@@ -296,29 +294,28 @@ public class ScopeNode extends ScopeMinNode {
             pred = pred instanceof NotNode not ? not.in(1) : IterPeeps.add(new NotNode(pred).peephole());
         // This is a zero/null test.
         // Compute the positive test type.
-        Type tnz   = pred._type.nonZero();
-        Type tcast = tnz.join(pred._type);
-        if( tcast != pred._type ) {
-            Node cast = new CastNode(tnz,ctrl,pred.keep()).peephole().keep();
-            _guards.add(pred);
-            _guards.add(cast);
-            replace(pred,cast);
-        }
+        Type tnz = pred._type.nonZero();
+        _addGuard(tnz,ctrl,pred);
 
         // Compute the negative test type.
         if( pred instanceof NotNode not ) {
             Node npred = not.in(1);
             Type tzero = npred._type.makeZero();
-            Type tzcast= tzero.join(npred._type);
-            if( tzcast != npred._type ) {
-                Node cast = new CastNode(tzero,ctrl,npred.keep()).peephole().keep();
-                _guards.add(npred);
-                _guards.add( cast);
-                replace(npred,cast);
-            }
+            _addGuard(tzero,ctrl,npred);
+        }
+    }
+
+    private void _addGuard(Type guard, Node ctrl, Node pred) {
+        Type tcast = guard.join(pred._type);
+        if( tcast != pred._type ) {
+            Node cast = new CastNode(tcast,ctrl,pred.keep()).peephole().keep();
+            _guards.add(pred);
+            _guards.add(cast);
+            replace(pred,cast);
         }
     }
 
+
     // Remove matching pred/cast pairs from this guarded region.
     public void removeGuards( Node ctrl ) {
         assert ctrl instanceof CFGNode;
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/ShlNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/ShlNode.java
index e167fd68..d3639ed7 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/ShlNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/ShlNode.java
@@ -44,7 +44,7 @@ public class ShlNode extends Node {
             if( (shl.value()&63)==0 )
                 return lhs;
             // (x + c) << i  =>  (x << i) + (c << i)
-            if( lhs instanceof AddNode add && add.addDep(this).in(2)._type instanceof TypeInteger c && c.isConstant() && c!=TypeInteger.ZERO ) {
+            if( lhs instanceof AddNode add && add.addDep(this).in(2)._type instanceof TypeInteger c && c.isConstant() ) {
                 long sum = c.value() << shl.value();
                 if( Integer.MIN_VALUE <= sum  && sum <= Integer.MAX_VALUE )
                     return new AddNode( new ShlNode(add.in(1),rhs).peephole(), Parser.con(sum) );
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/ShrNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/ShrNode.java
index b8c226bd..6f4a2c6c 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/ShrNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/ShrNode.java
@@ -2,7 +2,6 @@ package com.seaofnodes.simple.node;
 
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-
 import java.util.BitSet;
 
 public class ShrNode extends Node {
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/StoreNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/StoreNode.java
index 44a56a93..5bc88aa5 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/StoreNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/StoreNode.java
@@ -71,7 +71,7 @@ public class StoreNode extends MemOpNode {
             return this;
         }
 
-        // Simple store-after-new on same address.  Should pick up the
+        // Simple store-after-new on same address.  Should pick up
         // an init-store being stomped by a first user store.
         if( mem() instanceof ProjNode st  && st .in(0) instanceof NewNode nnn &&
             ptr() instanceof ProjNode ptr && ptr.in(0) == nnn &&
@@ -86,7 +86,7 @@ public class StoreNode extends MemOpNode {
             val()._type.isHighOrConst() &&
             // Must have exactly one use of "this" or you get weird
             // non-serializable memory effects in the worse case.
-            //checkOnlyUse(st) &&
+            checkOnlyUse(st) &&
             // Folding away a broken store
             err()==null ) {
             nnn.setDef(nnn.findAlias(_alias),val());
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/SubNode.java
index 5d6c2643..339c65ca 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/SubNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/SubNode.java
@@ -3,7 +3,6 @@ package com.seaofnodes.simple.node;
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-
 import java.util.BitSet;
 
 public class SubNode extends Node {
@@ -25,6 +24,9 @@ public class SubNode extends Node {
         Type t1 = in(1)._type, t2 = in(2)._type;
         if( t1.isHigh() || t2.isHigh() )
             return TypeInteger.TOP;
+        // Sub of same is 0
+        if( in(1)==in(2) )
+            return TypeInteger.ZERO;
         if( t1 instanceof TypeInteger i1 &&
             t2 instanceof TypeInteger i2 ) {
             if (i1.isConstant() && i2.isConstant())
@@ -35,9 +37,6 @@ public class SubNode extends Node {
                 i2._min != Long.MIN_VALUE  )
                 return TypeInteger.make(i1._min-i2._max,i1._max-i2._min);
         }
-        // Sub of same is 0
-        if( in(1)==in(2) )
-            return TypeInteger.ZERO;
 
         return TypeInteger.BOT;
     }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java b/chapter18/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
index 1d147cf6..4557a29e 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
@@ -21,8 +21,8 @@ public class ToFloatNode extends Node {
     @Override
     public Type compute() {
         if (in(1)._type instanceof TypeInteger i0 && i0.isConstant() )
-            return TypeFloat.constant(i0.value());
-        return TypeFloat.BOT;
+            return i0.value()==0 ? Type.NIL : TypeFloat.constant(i0.value());
+        return TypeFloat.F64;
     }
 
     @Override public Node idealize() { return null; }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/Field.java b/chapter18/src/main/java/com/seaofnodes/simple/type/Field.java
index 39f7fcc2..1ed75fe4 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/Field.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/Field.java
@@ -37,7 +37,7 @@ public class Field extends Type {
     @Override public Field makeRO() { return _final ? this : make(_fname,_type.makeRO(),_alias,true);  }
     @Override public boolean isFinal() { return _final && _type.isFinal(); }
 
-    public static final Field TEST = make("test",TypeInteger.ZERO,-2,false);
+    public static final Field TEST = make("test",Type.NIL,-2,false);
     public static void gather(ArrayList<Type> ts) { ts.add(TEST); }
 
     @Override Field xmeet( Type that ) {
@@ -52,12 +52,7 @@ public class Field extends Type {
 
     @Override public Field glb() {
         Type glb = _type.glb();
-        return glb==_type ? this : make(_fname,glb,_alias,_final);
-    }
-
-    @Override public Field lub() {
-        Type lub = _type.lub();
-        return lub==_type ? this : make(_fname,lub,_alias,_final);
+        return (glb==_type && _final) ? this : make(_fname,glb,_alias,true);
     }
 
     // Override in subclasses
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java b/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java
index 70e2dccf..5104f080 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/Type.java
@@ -31,39 +31,48 @@ public class Type {
     static final byte TTOP    = 1; // Top    (ANY)
     static final byte TCTRL   = 2; // Ctrl flow bottom
     static final byte TXCTRL  = 3; // Ctrl flow top (mini-lattice: any-xctrl-ctrl-all)
-    static final byte TSIMPLE = 4; // End of the Simple Types
-    static final byte TINT    = 5; // All Integers; see TypeInteger
-    static final byte TFLT    = 6; // All Integers; see TypeInteger
-    static final byte TTUPLE  = 7; // Tuples; finite collections of unrelated Types, kept in parallel
-    static final byte TMEM    = 8; // All memory (alias 0) or A slice of memory - with specific alias
-    static final byte TMEMPTR = 9; // Memory pointer type
-    static final byte TSTRUCT =10; // Structs; tuples with named fields
-    static final byte TFLD    =11; // Fields into struct
-    static final byte TARRAY  =12; // Array
-    static final byte TFUNPTR =13; // Function
+    static final byte TNIL    = 4; // low null of all flavors
+    static final byte TXNIL   = 5; // high or choice null
+    static final byte TSIMPLE = 6; // End of the Simple Types
+
+    static final byte TPTR    = 7; // All nil-able scalar values
+    static final byte TINT    = 8; // All Integers; see TypeInteger
+    static final byte TFLT    = 9; // All Floats  ; see TypeFloat
+    static final byte TMEMPTR =10; // Memory pointer to a struct type
+    static final byte TFUNPTR =11; // Function pointer; unique signature and code address (just a bit)
+    static final byte TTUPLE  =12; // Tuples; finite collections of unrelated Types, kept in parallel
+    static final byte TMEM    =13; // All memory (alias 0) or A slice of memory - with specific alias
+    static final byte TSTRUCT =14; // Structs; tuples with named fields
+    static final byte TFLD    =15; // Named fields in structs
 
     public final byte _type;
 
     public boolean is_simple() { return _type < TSIMPLE; }
-    private static final String[] STRS = new String[]{"Bot","Top","Ctrl","~Ctrl"};
+    private static final String[] STRS = new String[]{"Bot","Top","Ctrl","~Ctrl","nil","~nil"};
     protected Type(byte type) { _type = type; }
 
     public static final Type BOTTOM   = new Type( TBOT   ).intern(); // ALL
     public static final Type TOP      = new Type( TTOP   ).intern(); // ANY
     public static final Type CONTROL  = new Type( TCTRL  ).intern(); // Ctrl
     public static final Type XCONTROL = new Type( TXCTRL ).intern(); // ~Ctrl
+    public static final Type NIL      = new Type( TNIL   ).intern(); // low null of all flavors
+    public static final Type XNIL     = new Type( TXNIL  ).intern(); // high or choice null
     public static Type[] gather() {
         ArrayList<Type> ts = new ArrayList<>();
         ts.add(BOTTOM);
         ts.add(CONTROL);
-        Field.gather(ts);
+        ts.add(NIL);
+        ts.add(XNIL);
+        TypeNil.gather(ts);
+        TypePtr.gather(ts);
         TypeInteger.gather(ts);
         TypeFloat.gather(ts);
-        TypeMem.gather(ts);
         TypeMemPtr.gather(ts);
+        TypeFunPtr.gather(ts);
+        TypeMem.gather(ts);
+        Field.gather(ts);
         TypeStruct.gather(ts);
         TypeTuple.gather(ts);
-        TypeFunPtr.gather(ts);
         int sz = ts.size();
         for( int i = 0; i < sz; i++ )
             ts.add(ts.get(i).dual());
@@ -71,12 +80,12 @@ public class Type {
     }
 
     // Is high or on the lattice centerline.
-    public boolean isHigh       () { return _type==TTOP || _type==TXCTRL; }
-    public boolean isHighOrConst() { return _type==TTOP || _type==TXCTRL; }
+    public boolean isHigh       () { return _type==TTOP || _type==TXCTRL || _type==TXNIL; }
+    public boolean isHighOrConst() { return isHigh() || isConstant(); }
 
     // Strict constant values, things on the lattice centerline.
     // Excludes both high and low values
-    public boolean isConstant() { return false; }
+    public boolean isConstant() { return _type==TNIL; }
 
     // ----------------------------------------------------------
 
@@ -88,7 +97,7 @@ public class Type {
     // to be immutable once defined.  The rationale for interning is
     // *correctness* with cyclic type definitions.  Simple structural recursive
     // checks go exponential with merely sharing, but with cycles they will
-    // stack overflow and crash.  Intering means we do not need to have sharing
+    // stack overflow and crash.  Interning means we do not need to have sharing
     // checks with every type compare, only during interning.
 
     // Factory method which interns "this"
@@ -127,6 +136,9 @@ public class Type {
         if( t == this ) return this;
         // Same-type is always safe in the subclasses
         if( _type==t._type ) return xmeet(t);
+        // TypeNil vs TypeNil meet
+        if( this instanceof TypeNil ptr0 && t instanceof TypeNil ptr1 )
+            return ptr0.nmeet(ptr1);
         // Reverse; xmeet 2nd arg is never "is_simple" and never equal to "this".
         if(   is_simple() ) return this.xmeet(t   );
         if( t.is_simple() ) return t   .xmeet(this);
@@ -141,18 +153,27 @@ public class Type {
         // ANY meet anything is thing; thing meet ALL is ALL
         if( _type==TBOT || t._type==TTOP ) return this;
         if( _type==TTOP || t._type==TBOT ) return    t;
-        // 'this' is {TCTRL,TXCTRL}
+
+        // RHS TypeNil vs NIL/XNIL
+        if( _type==  TNIL ) return t instanceof TypeNil ptr ? ptr.meet0() : (t._type==TXNIL ? TypePtr.PTR : BOTTOM);
+        if( _type== TXNIL ) return t instanceof TypeNil ptr ? ptr.meetX() : (t._type== TNIL ? TypePtr.PTR : BOTTOM);
+        // 'this' is only {TCTRL,TXCTRL}
+        // Other non-simple RHS things bottom out
         if( !t.is_simple() ) return BOTTOM;
-        // 't' is {TCTRL,TXCTRL}
+        // If RHS is NIL/XNIL
+        if( t._type==TNIL || t._type==TXNIL ) return BOTTOM;
+        // Both are {TCTRL,TXCTRL} and unequal to each other
         return _type==TCTRL || t._type==TCTRL ? CONTROL : XCONTROL;
     }
 
     public Type dual() {
         return switch( _type ) {
-        case TBOT -> TOP;
-        case TTOP -> BOTTOM;
-        case TCTRL -> XCONTROL;
-        case TXCTRL -> CONTROL;
+        case TBOT  -> TOP;
+        case TTOP  -> BOTTOM;
+        case TCTRL ->XCONTROL;
+        case TXCTRL-> CONTROL;
+        case TNIL  ->XNIL;
+        case TXNIL -> NIL;
         default -> throw Utils.TODO(); // Should not reach here
         };
     }
@@ -168,19 +189,13 @@ public class Type {
     // True if this "isa" t; e.g. 17 isa TypeInteger.BOT
     public boolean isa( Type t ) { return meet(t)==t; }
 
-    /** Compute greatest lower bound in the lattice */
-    public Type glb() { return _type==TCTRL ? CONTROL : BOTTOM; }
-    /** Compute least upper bound in the lattice */
-    public Type lub() { return _type==TCTRL ? XCONTROL : TOP; }
+    public Type nonZero() { return TypePtr.NPTR; }
 
-    // Make an initial/default version of this type.  Typically, 0 for integers
-    // and null for nullable pointers.
-    public Type makeInit() { return this; }
     // Make a zero version of this type, 0 for integers and null for pointers.
-    public Type makeZero() { return null; }
-    // Make a non-zero version of this type, if possible.  Integers attempt to
-    // exclude zero from their range and pointers become not-null.
-    public Type nonZero() { return glb(); }
+    public Type makeZero() { return Type.NIL; }
+
+    /** Compute greatest lower bound in the lattice */
+    public Type glb() { return Type.NIL; }
 
     // Is forward-reference
     public boolean isFRef() { return false; }
@@ -207,7 +222,7 @@ public class Type {
         return print(new SB()).toString();
     }
 
-    public SB  print(SB sb) { return is_simple() ? sb.p(STRS[_type]) : sb;}
+    public SB  print(SB sb) { return sb.p(str()); }
     public SB gprint(SB sb) { return print(sb); }
 
     // This is used by error messages, and is a shorted print.
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFloat.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
index a11eec90..143adbcd 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
@@ -6,104 +6,90 @@ import java.util.ArrayList;
 /**
  * Float Type
  */
-public class TypeFloat extends Type {
+public class TypeFloat extends TypeNil {
 
-    public final static TypeFloat TOP = make((byte)-64, 0);
-    public final static TypeFloat T32 = make((byte)-32, 0);
-    public final static TypeFloat ZERO= make((byte)  0, 0);
-    public final static TypeFloat B32 = make((byte) 32, 0);
-    public final static TypeFloat BOT = make((byte) 64, 0);
+    public final static TypeFloat  ONE = constant(1.0);
+    public final static TypeFloat  F32 = make((byte)3, true, 0);
+    public final static TypeFloat NF64 = make((byte)2,false, 0);
+    public final static TypeFloat  F64 = make((byte)3,false, 0);
 
-    /** +/-64 for double; +/-32 for float, or 0 for constants */
-    public final byte _sz;
+    // true for 32bits, false for 64bits
+    public final boolean _f32;
 
     /**
      * The constant value or 0
      */
     public final double _con;
 
-    private TypeFloat(byte sz, double con) {
-        super(TFLT);
-        _sz  = sz ;
+    private TypeFloat(byte nil, boolean f32, double con) {
+        super(TFLT,nil);
+        assert !isConstant() || ((float)con == con) == f32;
+        _f32 = f32;
         _con = con;
     }
-    private static TypeFloat make(byte sz, double con) {
-        return new TypeFloat(sz,con).intern();
+    private static TypeFloat make(byte nil, boolean f32, double con) {
+        return new TypeFloat(nil,f32,con).intern();
+    }
+    @Override public TypeFloat makeFrom(byte nil) {
+        return nil==_nil ? this : make(nil,_f32,_con);
     }
 
-    public static TypeFloat constant(double con) { return make((byte)0, con); }
-
-    public static void gather(ArrayList<Type> ts) { ts.add(ZERO); ts.add(BOT); ts.add(B32); ts.add(constant(3.141592653589793)); }
+    public static TypeFloat constant(double con) { assert con!=0; return make((byte)2,((float)con)==con, con); }
 
-    // FIXME this display format is problematic
-    // In visualizer '#' gets prepended if its a constant
-    @Override
-    public SB print(SB sb) {
-        if( this==TOP ) return sb.p("FltTop");
-        if( this==T32 ) return sb.p("F32Top");
-        if( this==B32 ) return sb.p("F32Bot");
-        if( this==BOT ) return sb.p("FltBot");
-        return sb.p(_con);
-    }
+    public static void gather(ArrayList<Type> ts) { ts.add(F64); ts.add(F32); ts.add(constant(3.141592653589793)); }
 
     @Override public String str() {
-        if( this==TOP ) return "~flt";
-        if( this==T32 ) return "~f32";
-        if( this==B32 ) return  "f32";
-        if( this==BOT ) return  "flt";
-        return ""+_con+(isF32() ? "f" : "");
+        if( isConstant() )
+            return ""+_con+(_f32 ? "f" : "");
+        String s = "";
+        if( isHigh() ) s = "~";
+        if( 1 <= _nil && _nil <= 2 ) // Disallow nil?
+            s += "n";
+        s += "f";
+        s += _f32 ? "32" : "lt";
+        return s;
     }
 
-    boolean isF32() { return ((float)_con)==_con; }
-    @Override public boolean isHigh()        { return _sz< 0; }
-    @Override public boolean isHighOrConst() { return _sz<=0; }
-    @Override public boolean isConstant()    { return _sz==0; }
-
-    @Override public int log_size() {
-        int sz = _sz==0 ? (isF32() ? 32 : 64) : Math.abs(_sz);
-        return _sz==32 ? 2 : 3;
-    }
+    @Override public boolean isConstant() { return _con!=0; }
+    @Override public int log_size() { return _f32 ? 2 : 3; }
 
     public double value() { return _con; }
 
     @Override
-    public Type xmeet(Type other) {
-        // Invariant from caller: 'this' != 'other' and same class (TypeFloat)
+    public TypeFloat xmeet(Type other) {
+        // Invariant from caller: 'this' != 'other' and same class (TypeFloat).
         TypeFloat i = (TypeFloat)other; // Contract
-        // Larger size in i1, smaller in i0
-        TypeFloat i0 = _sz < i._sz ? this : i;
-        TypeFloat i1 = _sz < i._sz ? i : this;
-
-        if( i1._sz== 64 ) return BOT;
-        if( i0._sz==-64 ) return i1;
-        if( i1._sz== 32 )
-            return i0._sz==0 && !i0.isF32() ? BOT : B32;
-        if( i1._sz!=  0 ) return i1;
-        // i1 is a constant
-        if( i0._sz==-32 )
-            return i1.isF32() ? i1 : BOT;
-        // Since both are constants, and are never equals (contract) unequals
-        // constants fall to bottom
-        return i0.isF32() && i1.isF32() ? B32 : BOT;
+        if(   isConstant() && i.isHigh() ) return i._f32 && !  _f32 ? NF64 : this;
+        if( i.isConstant() &&   isHigh() ) return   _f32 && !i._f32 ? NF64 :  i  ;
+
+
+        // From online Karnaugh map; if both values are small the result is
+        // small, otherwise the result is small if the otherside is high.
+        boolean f32 = (_f32&i._f32) | (i.isHigh()&_f32) | (isHigh()&i._f32);
+        return make(xmeet0(i), f32, 0);
     }
 
     @Override
     public Type dual() {
-        if( _sz==0 ) return this; // Constants are a self-dual
-        return make((byte)-_sz,0);
+        if( isConstant() ) return this; // Constants are a self-dual
+        return make(dual0(),_f32,0);
     }
 
-    @Override public Type glb() { return BOT; }
-    @Override public Type lub() { return TOP; }
-    @Override public TypeFloat makeInit() { return ZERO; }
-    @Override public TypeFloat makeZero() { return ZERO; }
+    // RHS is NIL
+    @Override Type meet0() {
+        // From high, falling to the least Float that contains a zero
+        return isHigh() || _f32 ? F32 : F64;
+    }
+
+
+    @Override public Type glb() { return F64; }
 
     @Override
-    int hash() { return (int)(Double.hashCode(_con) ^ _sz); }
+    int hash() { return (int)(Double.hashCode(_con) ^ (_f32 ? 2048 : 0) ^ super.hash()); }
     @Override
     public boolean eq( Type t ) {
         TypeFloat i = (TypeFloat)t; // Contract
-        return _con==i._con && _sz==i._sz;
+        return _con==i._con && _f32==i._f32 && super.eq(i);
     }
 
 }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java
index 3a0c91ea..9d4e5795 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java
@@ -32,6 +32,8 @@ public class TypeFunPtr extends Type {
     }
 
     public static TypeFunPtr make( TypeTuple sig, long fidxs ) { return new TypeFunPtr(sig,fidxs).intern(); }
+    // Make a TFP with all functions
+    public static TypeFunPtr make( TypeTuple sig, boolean nil ) { return new TypeFunPtr(sig,-2|(nil ? 1 : 0)).intern(); }
 
     public static TypeFunPtr BOT     = make(TypeTuple.SIGBOT,-1);
     public static TypeFunPtr TOP     = BOT.dual();
@@ -51,12 +53,8 @@ public class TypeFunPtr extends Type {
     public TypeFunPtr dual() { return TypeFunPtr.make(_sig.dual(), ~_fidxs); }
 
     @Override public TypeFunPtr glb() { throw Utils.TODO(); }
-    @Override public TypeFunPtr lub() { throw Utils.TODO(); }
     // Is forward-reference
     @Override public boolean isFRef() { return false; }
-    @Override public Type makeInit() { return (_fidxs&1)==1 ? NULLPTR : Type.TOP; }
-    @Override public Type makeZero() { return NULLPTR; }
-    @Override public Type  nonZero() { return VOIDPTR; }
 
     @Override public boolean isHigh() { return this==TOP; }
     @Override public boolean isConstant() { return Long.bitCount(_fidxs)==1; }
@@ -73,38 +71,48 @@ public class TypeFunPtr extends Type {
         return _sig == ptr._sig  && _fidxs == ptr._fidxs;
     }
 
+
+    @Override public String str() {
+        if( this== NULLPTR) return "null";
+        if( this== VOIDPTR) return "*void";
+        return print(new SB()).toString();
+    }
+
     // [void,name,MANY]*[,?]
-    @Override
-    public SB print(SB sb) {
+    @Override public SB print(SB sb) {
         if( this== NULLPTR) return sb.p("null");
         if( this== VOIDPTR) return sb.p("*void");
         sb.p("{ ");
         for( int i=1; i<_sig._types.length; i++ )
             _sig._types[i].print(sb).p(" ");
         _sig._types[0].print(sb.p("-> "));
-        sb.p(String.format(" #%X",_fidxs));
-        sb.p("}");
+        sb.p(" #");
+        long fidxs = _fidxs&-2; // Strip off the null flag bit
+        String fidx = fidxs==0 ? ""
+            : Long.bitCount(fidxs) == 1 ? ""+Long.numberOfTrailingZeros(fidxs)
+            : fidxs == -2 ? "ALL"
+            : "b"+Long.toBinaryString(fidxs); // Just some function bits
+        sb.p(fidx).p("}");
         if( (_fidxs&1)==1 ) sb.p("?");
         return sb;
     }
-    @Override
-    public SB gprint(SB sb) {
+
+    @Override public SB gprint(SB sb) {
         if( this== NULLPTR) return sb.p("null");
         if( this== VOIDPTR) return sb.p("*void");
         sb.p("{ ");
         for( int i=1; i<_sig._types.length; i++ )
             _sig._types[i].gprint(sb).p(" ");
         _sig._types[0].gprint(sb.p("-> "));
-        sb.p(String.format(" #%X",_fidxs));
-        sb.p("}");
+        sb.p(" #");
+        long fidxs = _fidxs&-2; // Strip off the null flag bit
+        String fidx = fidxs==0 ? ""
+            : Long.bitCount(fidxs) == 1 ? ""+Long.numberOfTrailingZeros(fidxs)
+            : fidxs == -2 ? "ALL"
+            : "b"+Long.toBinaryString(fidxs); // Just some function bits
+        sb.p(fidx).p("}");
         if( (_fidxs&1)==1 ) sb.p("?");
         return sb;
     }
 
-    @Override public String str() {
-        if( this== NULLPTR) return "null";
-        if( this== VOIDPTR) return "*void";
-        return print(new SB()).toString();
-    }
-
 }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeInteger.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
index 2be4f4d8..77b280f3 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
@@ -9,17 +9,19 @@ import java.util.ArrayList;
  */
 public class TypeInteger extends Type {
 
-    public final static TypeInteger TOP = make(false, 0);
-    public final static TypeInteger BOT = make(false, 1);
     public final static TypeInteger ZERO= make(0,0);
-    public final static TypeInteger U1  = make(0,1);
-    public final static TypeInteger BOOL= U1;
     public final static TypeInteger FALSE=ZERO;
     public final static TypeInteger TRUE= make(1,1);
+
+    public final static TypeInteger I1  = make(-1,0);
     public final static TypeInteger I8  = make(-128,127);
     public final static TypeInteger I16 = make(-32768,32767);
     public final static TypeInteger I32 = make(-1L<<31,(1L<<31)-1);
+    public final static TypeInteger BOT = make(Long.MIN_VALUE,Long.MAX_VALUE);
+    public final static TypeInteger TOP = BOT.dual();
 
+    public final static TypeInteger U1  = make(0,1);
+    public final static TypeInteger BOOL= U1;
     public final static TypeInteger U8  = make(0,255);
     public final static TypeInteger U16 = make(0,65535);
     public final static TypeInteger U32 = make(0,(1L<<32)-1);
@@ -27,45 +29,50 @@ public class TypeInteger extends Type {
     /**
      * Describes an integer *range* - everything from min to max; both min and
      * max are inclusive.  If min==max, this is a constant.
-     *
+     * <br>
      * If min <= max, this is a  below center (towards bottom).
      * If min >  max, this is an above center (towards top).
      */
     public final long _min, _max;
 
-    private TypeInteger(long min, long max) { super(TINT); _min = min; _max = max; }
-    public static TypeInteger make(long lo, long hi) {  return new TypeInteger(lo,hi).intern();  }
-    public static TypeInteger make(boolean is_con, long con) {
-        return make(is_con ? con : (con==0 ? Long.MAX_VALUE : Long.MIN_VALUE),
-                    is_con ? con : (con==0 ? Long.MIN_VALUE : Long.MAX_VALUE));
+    private TypeInteger(long min, long max) {
+        super(TINT);
+        _min = min;
+        _max = max;
     }
 
-    public static TypeInteger constant(long con) { return make(true, con); }
+    // Strict non-zero contract
+    public static TypeInteger make(long lo, long hi) { return new TypeInteger(lo,hi).intern(); }
 
-    public static void gather(ArrayList<Type> ts) { ts.add(ZERO); ts.add(BOT); ts.add(U1); ts.add(U8); }
+    public static TypeInteger constant(long con) { return make(con, con); }
 
-    // FIXME this display format is problematic
-    // In visualizer '#' gets prepended if its a constant
-    @Override
-    public SB print(SB sb) { return sb.p(str()); }
+    public static void gather(ArrayList<Type> ts) { ts.add(I32); ts.add(BOT); ts.add(U1); ts.add(I1); ts.add(U8); }
 
     @Override public String str() {
-        if( this==TOP ) return "~int";
-        if( this==BOT ) return  "int";
-        if( this==BOOL) return ("bool");
-        if( this==I8  ) return ("i8");
-        if( this==I16 ) return ("i16");
-        if( this==I32 ) return ("i32");
-        if( this==U8  ) return ("u8");
-        if( this==U16 ) return ("u16");
-        if( this==U32 ) return ("u32");
         if( isConstant() ) return ""+_min;
-        return "["+_min+"-"+_max+"]";
+        long lo = _min, hi = _max;
+        String x = "";
+        if( hi < lo ) {
+            lo = _max;  hi = _min;
+            x = "~";
+        }
+        return x+_str(lo,hi);
+    }
+    private static String _str(long lo, long hi) {
+        if( lo==Long.MIN_VALUE && hi==Long.MAX_VALUE ) return "int";
+        if( lo==       0 && hi==         1 ) return "bool";
+        if( lo==      -1 && hi==         0 ) return "i1";
+        if( lo==    -128 && hi==       127 ) return "i8";
+        if( lo==  -32768 && hi==     32767 ) return "i16";
+        if( lo== -1L<<31 && hi==(1L<<31)-1 ) return "i32";
+        if( lo==       0 && hi==      255  ) return "u8";
+        if( lo==       0 && hi==     65535 ) return "u16";
+        if( lo==       0 && hi==(1L<<32)-1 ) return "u32";
+        return "["+lo+"-"+hi+"]";
     }
 
-    @Override public boolean isHigh       () { return _min >  _max; }
-    @Override public boolean isHighOrConst() { return _min >= _max; }
-    @Override public boolean isConstant   () { return _min == _max; }
+    @Override public boolean isHigh    () { return _min >  _max; }
+    @Override public boolean isConstant() { return _min == _max; }
 
     @Override public int log_size() {
         if( this==I8  || this==U8 || this==BOOL ) return 0; // 1<<0 == 1 bytes
@@ -84,8 +91,6 @@ public class TypeInteger extends Type {
     public long mask() {
         if( isHigh() ) return 0;
         if( isConstant() ) return _min;
-        //if( _min<0 ) return -1L;
-        //if( _max==Long.MAX_VALUE ) return -1L;
         // Those bit positions which differ min to max
         long x = _min ^ _max;
         // Highest '1' bit in the differ set.  Since the range is from min to
@@ -105,19 +110,17 @@ public class TypeInteger extends Type {
     }
 
     @Override public TypeInteger dual() { return make(_max,_min); }
-    @Override public TypeInteger glb() { return BOT; }
-    @Override public TypeInteger lub() { return TOP; }
-    @Override public TypeInteger makeInit() { return ZERO; }
-    @Override public TypeInteger makeZero() { return ZERO; }
+
     @Override public TypeInteger nonZero() {
         if( isHigh() ) return this;
         if( _min==0 ) return make(1,Math.max(_max,1)); // specifically good on BOOL
         if( _max==0 ) return make(_min,-1);
         return this;
     }
-    @Override int hash() { return (int)((_min ^ (_min>>32)) *(_max ^ (_max>>32))); }
-    @Override
-    public boolean eq( Type t ) {
+    @Override public Type makeZero() { return TypeInteger.ZERO; }
+    @Override public TypeInteger glb() { return BOT; }
+    @Override int hash() { return Utils.fold(_min) * Utils.fold(_max); }
+    @Override public boolean eq( Type t ) {
         TypeInteger i = (TypeInteger)t; // Contract
         return _min==i._min && _max==i._max;
     }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMem.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMem.java
index 007a18d6..60b3612f 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMem.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMem.java
@@ -25,7 +25,7 @@ public class TypeMem extends Type {
     public static final TypeMem TOP = make(0, Type.TOP   );
     public static final TypeMem BOT = make(0, Type.BOTTOM);
 
-    public static void gather(ArrayList<Type> ts) { ts.add(make(1,TypeInteger.ZERO)); ts.add(BOT); }
+    public static void gather(ArrayList<Type> ts) { ts.add(make(1,Type.NIL)); ts.add(make(1,TypeInteger.ZERO)); ts.add(BOT); }
 
     @Override
     TypeMem xmeet(Type t) {
@@ -45,25 +45,20 @@ public class TypeMem extends Type {
     }
 
     @Override public Type glb() { return make(_alias,_t.glb()); }
-    @Override public Type lub() { return make(_alias,_t.lub()); }
 
-    @Override
-    int hash() { return 9876543 + _alias + _t.hashCode(); }
+    @Override int hash() { return 9876543 + _alias + _t.hashCode(); }
 
-    @Override
-    boolean eq(Type t) {
+    @Override boolean eq(Type t) {
         TypeMem that = (TypeMem) t; // Invariant
         return _alias == that._alias && _t == that._t;
     }
 
-    @Override
-    public SB print(SB sb) {
+    @Override public SB print(SB sb) {
         sb.p("#");
         if( _alias==0 ) return sb.p(_t._type==TTOP ? "TOP" : "BOT");
         return _t.print(sb.p(_alias).p(":"));
     }
-    @Override
-    public SB gprint(SB sb) {
+    @Override public SB gprint(SB sb) {
         sb.p("#");
         if( _alias==0 ) return sb.p(_t._type==TTOP ? "TOP" : "BOT");
         return _t.gprint(sb.p(_alias).p(":"));
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
index b675eef5..d17cfd39 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
@@ -1,6 +1,7 @@
 package com.seaofnodes.simple.type;
 
 import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.Utils;
 import java.util.ArrayList;
 
 /**
@@ -12,9 +13,9 @@ import java.util.ArrayList;
  * The distinguished *$BOT ptr represents union of *void and Null.
  * The distinguished *$TOP ptr represents the dual of *$BOT.
  */
-public class TypeMemPtr extends Type {
+public class TypeMemPtr extends TypeNil {
     // A TypeMemPtr is pair (obj,nil)
-    // where obj is a TypeStruct, possibly TypeStruct.BOT
+    // where obj is a TypeStruct, possibly TypeStruct.BOT/TOP
     // where nil is an explicit null is allowed or not
 
     // Examples:
@@ -24,82 +25,70 @@ public class TypeMemPtr extends Type {
     // (TOP   ,true ) - a nil
 
     public final TypeStruct _obj;
-    public final boolean _nil;
 
-    private TypeMemPtr(TypeStruct obj, boolean nil) {
-        super(TMEMPTR);
+    private TypeMemPtr(byte nil, TypeStruct obj) {
+        super(TMEMPTR,nil);
         assert obj!=null;
         _obj = obj;
-        _nil = nil;
     }
-    public static TypeMemPtr make(TypeStruct obj, boolean nil) { return new TypeMemPtr(obj, nil).intern(); }
-    public static TypeMemPtr make(TypeStruct obj) { return make(obj, false); }
-    public TypeMemPtr makeFrom(TypeStruct obj) { return obj==_obj ? this : make(obj, _nil); }
-    public TypeMemPtr makeFrom(boolean nil) { return nil==_nil ? this : make(_obj, nil); }
+    public static TypeMemPtr make(byte nil, TypeStruct obj) { return new TypeMemPtr(nil, obj).intern(); }
+    public static TypeMemPtr make(TypeStruct obj) { return make((byte)3, obj); }
+    public TypeMemPtr makeFrom(TypeStruct obj) { return obj==_obj ? this : make(_nil, obj); }
+    @Override public TypeMemPtr makeFrom(byte nil) { return nil==_nil ? this : make(nil,_obj); }
     @Override public TypeMemPtr makeRO() { return makeFrom(_obj.makeRO()); }
     @Override public boolean isFinal() { return _obj.isFinal(); }
 
     // An abstract pointer, pointing to either a Struct or an Array.
-    // Can also be null or not.
-    public static TypeMemPtr BOT = make(TypeStruct.BOT,true);
+    // Can also be null or not, so 4 choices {TOP,BOT} x {nil,not}
+    public static TypeMemPtr BOT = make((byte)3, TypeStruct.BOT);
     public static TypeMemPtr TOP = BOT.dual();
-    // An abstract null (can be Struct or Array) or not-null C void*
-    public static TypeMemPtr NULLPTR = make(TypeStruct.TOP,true);
-    public static TypeMemPtr VOIDPTR = NULLPTR.dual(); // A bottom mix of not-null ptrs, like C's void* but not null
+    public static TypeMemPtr NOTBOT = make((byte)2,TypeStruct.BOT);
 
-    public static TypeMemPtr TEST= make(TypeStruct.TEST,false);
-    public static void gather(ArrayList<Type> ts) { ts.add(NULLPTR); ts.add(BOT); ts.add(TEST); }
+    public static TypeMemPtr TEST= make((byte)2, TypeStruct.TEST);
+    public static void gather(ArrayList<Type> ts) { ts.add(NOTBOT); ts.add(BOT); ts.add(TEST); }
 
     @Override
-    Type xmeet(Type t) {
+    public TypeNil xmeet(Type t) {
         TypeMemPtr that = (TypeMemPtr) t;
-        return TypeMemPtr.make((TypeStruct)_obj.meet(that._obj), _nil | that._nil);
+        return TypeMemPtr.make(xmeet0(that), (TypeStruct)_obj.meet(that._obj));
     }
 
     @Override
-    public TypeMemPtr dual() { return TypeMemPtr.make(_obj.dual(), !_nil); }
+    public TypeMemPtr dual() { return TypeMemPtr.make( dual0(), _obj.dual()); }
 
-    @Override public TypeMemPtr glb() { return make(_obj.glb(),true ); }
-    @Override public TypeMemPtr lub() { return make(_obj.lub(),false); }
+    // RHS is NIL
+    @Override Type meet0() {
+        // NOT DOING DUAL
+        return _nil==3 ? this : make((byte)3,_obj);
+    }
+
+    @Override public TypeMemPtr glb() { return make((byte)3,_obj.glb()); }
     // Is forward-reference
     @Override public boolean isFRef() { return _obj.isFRef(); }
-    @Override public Type makeInit() { return _nil ? NULLPTR : Type.TOP; }
-    @Override public Type makeZero() { return NULLPTR; }
-    @Override public Type nonZero() { return VOIDPTR; }
-
-    @Override public boolean isHigh() { return this==TOP; }
-    @Override public boolean isConstant() { return this==NULLPTR; }
-    @Override public boolean isHighOrConst() { return this==TOP || this==NULLPTR; }
 
     @Override public int log_size() { return 2; } // (1<<2)==4-byte pointers
 
-    @Override
-    int hash() { return _obj.hashCode() ^ (_nil ? 1024 : 0); }
+    @Override int hash() { return _obj.hashCode() ^ super.hash(); }
 
-    @Override
-    boolean eq(Type t) {
+    @Override boolean eq(Type t) {
         TypeMemPtr ptr = (TypeMemPtr)t; // Invariant
-        return _obj == ptr._obj  && _nil == ptr._nil;
-    }
-
-    // [void,name,MANY]*[,?]
-    @Override
-    public SB print(SB sb) {
-        if( this== NULLPTR) return sb.p("null");
-        if( this== VOIDPTR) return sb.p("*void");
-        return _obj.print(sb.p("*")).p(_nil ? "?" : "");
-    }
-    @Override
-    public SB gprint(SB sb) {
-        if( this== NULLPTR) return sb.p("null");
-        if( this== VOIDPTR) return sb.p("*void");
-        return _obj.gprint(sb.p("*")).p(_nil ? "?" : "");
+        return _obj == ptr._obj  && super.eq(ptr);
     }
 
     @Override public String str() {
-        if( this== NULLPTR) return "null";
-        if( this== VOIDPTR) return "*void";
-        return "*"+_obj.str()+(_nil ? "?" : "");
+        if( this== NOTBOT) return "*void";
+        if( this==    BOT) return "*void?";
+        return x()+"*"+_obj.str()+q();
     }
 
+    @Override public SB print(SB sb) {
+        if( this== NOTBOT) return sb.p("*void");
+        if( this==    BOT) return sb.p("*void?");
+        return _obj.print(sb.p(x()).p("*")).p(q());
+    }
+    @Override public SB gprint(SB sb) {
+        if( this== NOTBOT) return sb.p("*void");
+        if( this==    BOT) return sb.p("*void?");
+        return _obj.gprint(sb.p(x()).p("*")).p(q());
+    }
 }
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeNil.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeNil.java
new file mode 100644
index 00000000..d8003d50
--- /dev/null
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeNil.java
@@ -0,0 +1,57 @@
+package com.seaofnodes.simple.type;
+
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.Utils;
+import java.util.ArrayList;
+
+/**
+ * Nil-able Scalar types
+ */
+public abstract class TypeNil extends Type {
+    // 0 = high-subclass choice nil
+    // 1 = high-subclass no nil
+    // 2 = low -subclass no nil
+    // 3 = low -subclass also nil
+    public final byte _nil;
+
+    TypeNil(byte t, byte nil ) { super(t); _nil = nil; }
+
+    public static void gather(ArrayList<Type> ts) { }
+
+    abstract TypeNil makeFrom(byte nil);
+
+    byte xmeet0(TypeNil that) { return (byte)Math.max(_nil,that._nil); }
+
+    byte dual0() { return (byte)(3-_nil); }
+
+    // RHS is NIL
+    abstract Type meet0();
+
+    // RHS is XNIL
+    Type meetX() {
+        return _nil==0 ? XNIL : (_nil<=2 ? TypePtr.NPTR : TypePtr.PTR);
+    }
+
+    Type nmeet(TypeNil tn) {
+        // Invariants: both are TypeNil subclasses and unequal classes.
+        // If this is TypePtr, we went to TypePtr.nmeet and not here.
+        // If that is TypePtr, this is not (invariant); reverse and go again.
+        if( tn instanceof TypePtr ts ) return ts.nmeet(this);
+
+        // Two mismatched TypeNil, no Scalar.
+        if( _nil==0 && tn._nil==0 ) return XNIL;
+        if( _nil<=2 && tn._nil<=2 ) return TypePtr.NPTR;
+        return TypePtr.PTR;
+    }
+
+    @Override public boolean isHigh       () { return _nil <= 1; }
+    @Override public boolean isConstant   () { return false; }
+    @Override public boolean isHighOrConst() { return isHigh() || isConstant(); }
+
+    final String q() { return _nil == 1 || _nil == 2 ? "" : "?"; }
+    final String x() { return isHigh() ? "~" : ""; }
+
+    int hash() { return _nil<<17; }
+
+    boolean eq(TypeNil ptr) { return _nil == ptr._nil; }
+}
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypePtr.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypePtr.java
new file mode 100644
index 00000000..e9091c25
--- /dev/null
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypePtr.java
@@ -0,0 +1,53 @@
+package com.seaofnodes.simple.type;
+
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.Utils;
+import java.util.ArrayList;
+
+/**
+ * Represents a Scalar; a single register-sized value.
+ */
+public class TypePtr extends TypeNil {
+
+    private TypePtr(byte nil) { super(TPTR,nil);  }
+
+    // An abstract pointer, pointing to either a Struct or an Array.
+    // Can also be null or not, so 4 choices {TOP,BOT} x {nil,not}
+    public static TypePtr XPTR = new TypePtr((byte)0).intern();
+    public static TypePtr XNPTR= new TypePtr((byte)1).intern();
+    public static TypePtr NPTR = new TypePtr((byte)2).intern();
+    public static TypePtr PTR  = new TypePtr((byte)3).intern();
+    private static final TypePtr[] PTRS = new TypePtr[]{XPTR,XNPTR,NPTR,PTR};
+
+    public static void gather(ArrayList<Type> ts) { ts.add(PTR); ts.add(NPTR); }
+
+    TypeNil makeFrom(byte nil) { throw Utils.TODO(); }
+
+    @Override public TypeNil xmeet(Type t) {
+        TypePtr that = (TypePtr) t;
+        return PTRS[xmeet0(that)];
+    }
+
+    @Override public TypePtr dual() { return PTRS[dual0()]; }
+
+    // High scalar loses, low scalar wins
+    @Override TypeNil nmeet(TypeNil tn) {
+        if( _nil==0 ) return tn; // High scalar loses
+        if( _nil==1 ) return tn.makeFrom(xmeet0(tn)); // High scalar loses
+        if( _nil==2 ) return tn._nil==3 ? PTR : NPTR; // Low scalar wins
+        return PTR; // this
+    }
+
+
+    // RHS is  NIL
+    @Override Type meet0() { return isHigh() ? NIL : PTR; }
+    // RHS is XNIL
+    // 0->xscalar, 1->nscalar, 2->nscalar, 3->scalar
+    @Override Type meetX() { return _nil==0 ? XNIL : (_nil==3 ? PTR : NPTR); }
+
+    @Override public TypePtr glb() { return PTR; }
+
+    private static final String[] STRS = new String[]{"~ptr","~nptr","nptr","ptr"};
+    @Override public String str() { return STRS[_nil]; }
+    @Override public SB print(SB sb) { return sb.p(str()); }
+}
diff --git a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeStruct.java b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
index c3ee5eb3..35bbe36c 100644
--- a/chapter18/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
+++ b/chapter18/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
@@ -49,7 +49,7 @@ public class TypeStruct extends Type {
 
     // Array
     public static TypeStruct makeAry(TypeInteger len, int lenAlias, Type body, int bodyAlias) {
-        assert !(body instanceof TypeMemPtr tmp && !tmp._nil);
+        assert body instanceof TypeInteger || (body instanceof TypeNil tn && tn._nil==3);
         return make("[" + body.str() + "]",
                     Field.make("#" ,len , lenAlias,true ),
                     Field.make("[]",body,bodyAlias,false));
@@ -58,10 +58,10 @@ public class TypeStruct extends Type {
     // A pair of self-cyclic types
     private static final TypeStruct S1F = makeFRef("S1");
     private static final TypeStruct S2F = makeFRef("S2");
-    public  static final TypeStruct S1  = make("S1", Field.make("a", TypeInteger.BOT, -1, false), Field.make("s2",TypeMemPtr.make(S2F,false),-2, false) );
-    private static final TypeStruct S2  = make("S2", Field.make("b", TypeFloat  .BOT, -3, false), Field.make("s1",TypeMemPtr.make(S1F,false),-4, false) );
+    public  static final TypeStruct S1  = make("S1", Field.make("a", TypeInteger.BOT, -1, false), Field.make("s2",TypeMemPtr.make((byte)2,S2F),-2, false) );
+    private static final TypeStruct S2  = make("S2", Field.make("b", TypeFloat  .F64, -3, false), Field.make("s1",TypeMemPtr.make((byte)2,S1F),-4, false) );
 
-    private static final TypeStruct ARY = makeAry(TypeInteger.BOT,-1,TypeFloat.BOT,-2);
+    private static final TypeStruct ARY = makeAry(TypeInteger.BOT,-1,TypeInteger.BOT,-2);
 
     public static void gather(ArrayList<Type> ts) { ts.add(TEST); ts.add(BOT); ts.add(S1); ts.add(S2); ts.add(ARY); }
 
@@ -143,22 +143,6 @@ public class TypeStruct extends Type {
                  return false;
         return true;
     }
-    @Override public TypeStruct lub() {
-        if( _lub() ) return this;
-        // Need to glb each field
-        Field[] flds = new Field[_fields.length];
-        for( int i=0; i<_fields.length; i++ )
-            flds[i] = _fields[i].lub();
-        return make(_name,flds);
-    }
-    private boolean _lub() {
-        if( _fields!=null )
-          for( Field f : _fields )
-              if( f.lub() != f )
-                 return false;
-        return true;
-    }
-
 
     // Is forward-reference
     @Override public boolean isFRef() { return _fields==null; }
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/BrainFuckTest.java b/chapter18/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
index 88d79215..b1ca7da9 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
@@ -23,7 +23,8 @@ public class BrainFuckTest {
 
         Parser parser = new Parser(
                 encoded + """
-var d = 0;
+
+int d = 0;
 u8[] !output = new u8[0];
 u8[] !data = new u8[100];
 
@@ -41,14 +42,14 @@ for( int pc = 0; pc < program#; pc++ ) {
         // Output a byte; increase the output array size
         var old = output;
         output = new u8[output# + 1];
-        for( var i = 0; i < old#; i++ )
+        for( int i = 0; i < old#; i++ )
             output[i] = old[i];
         output[old#] = data[d]; // Add the extra byte on the end
     } else if (command == 44) {
         data[d] = 42;
     } else if (command == 91) {
         if (data[d] == 0) {
-            for( var d = 1; d > 0; ) {
+            for( int d = 1; d > 0; ) {
                 command = program[++pc];
                 if (command == 91) d++;
                 if (command == 93) d--;
@@ -56,7 +57,7 @@ for( int pc = 0; pc < program#; pc++ ) {
         }
     } else if (command == 93) {
         if (data[d]) {
-            for( var d = 1; d > 0; ) {
+            for( int d = 1; d > 0; ) {
                 command = program[--pc];
                 if (command == 93) d++;
                 if (command == 91) d--;
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter01Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter01Test.java
index f7524c17..44f1af0d 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter01Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter01Test.java
@@ -93,7 +93,7 @@ public class Chapter01Test {
             new Parser("return 1;}").parse();
             fail();
         } catch( RuntimeException e ) {
-            assertEquals("Syntax error, unexpected }",e.getMessage());
+            assertEquals("Syntax error, unexpected: }",e.getMessage());
         }
     }
 
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter03Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter03Test.java
index 4525918c..62304b38 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter03Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter03Test.java
@@ -1,7 +1,6 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.type.TypeInteger;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter10Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter10Test.java
index d41c83d8..435a2012 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter10Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter10Test.java
@@ -117,7 +117,7 @@ bar.a = 1;
 return bar.a;
 """);
         try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Type null is not of declared type *Bar",e.getMessage()); }
+        catch( Exception e ) { assertEquals("Type nil is not of declared type *Bar",e.getMessage()); }
     }
 
     @Test
@@ -143,7 +143,7 @@ bar.a = 1;
 return bar.a;
 """);
         try { parser.parse(); fail(); }
-        catch( Exception e ) { assertEquals("Type null is not of declared type *Bar", e.getMessage()); }
+        catch( Exception e ) { assertEquals("Type nil is not of declared type *Bar", e.getMessage()); }
     }
 
     @Test
@@ -156,7 +156,7 @@ if( bar ) bar.a = 1;
 return bar;
 """);
         StopNode stop = parser.parse(false).iterate();
-        assertEquals("return Phi(Region,(*void)Phi(Region,null,Bar),null);", stop.toString());
+        assertEquals("return Phi(Region,nil,Bar);", stop.toString());
     }
 
     @Test
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index a70a5f33..39824d39 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -43,7 +43,7 @@ while( 1 ) {
 return guess;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,(flt)arg,(((ToFloat/Phi_guess)+Phi_guess)/2.0));", stop.toString());
+        assertEquals("return Phi(Loop,(flt)arg,(((ToFloat/Phi_guess)+Phi_guess)/2.0f));", stop.toString());
         assertEquals(3.0, Evaluator.evaluate(stop,  9));
         assertEquals(1.414213562373095, Evaluator.evaluate(stop,  2));
     }
@@ -56,7 +56,7 @@ flt x = arg;
 return x+1==x;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return ((flt)arg==(ToFloat+1.0));", stop.toString());
+        assertEquals("return ((flt)arg==(ToFloat+1.0f));", stop.toString());
         assertEquals(0L, Evaluator.evaluate(stop, 1));
     }
 }
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter13Test.java
index 30d9b147..a3e7c47f 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter13Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -87,7 +87,7 @@ N n = new N;
 return n.next;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return null;", stop.toString());
+        assertEquals("return nil;", stop.toString());
     }
 
     @Test
@@ -113,7 +113,7 @@ N n = new N { next = null; }
 return n.next;
 """);
         try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Type null is not of declared type *M",e.getMessage()); }
+        catch( Exception e ) { assertEquals("Type nil is not of declared type *M",e.getMessage()); }
     }
 
     @Test
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index 23c82358..f4e35fe5 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -158,11 +158,11 @@ return (arg | 123 ^ 456) >>> 1;
         Parser parser = new Parser(
 """
 flt f = arg;
-arg = f & 0;
+arg = f & 1;
 return arg;
 """);
         try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot '&' FltBot",e.getMessage()); }
+        catch( Exception e ) { assertEquals("Cannot '&' flt",e.getMessage()); }
     }
 
     @Test
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index 4e2682dc..e7dec389 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -3,9 +3,7 @@ package com.seaofnodes.simple;
 import com.seaofnodes.simple.evaluator.Evaluator;
 import com.seaofnodes.simple.node.StopNode;
 import org.junit.Test;
-import org.junit.Ignore;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 public class Chapter15Test {
 
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter17Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter17Test.java
index 4a7e959a..9a2676d3 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter17Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter17Test.java
@@ -337,7 +337,7 @@ flt f=arg?1:1.2;
 return f;   // missing widening
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,1.0,1.2);", stop.toString());
+        assertEquals("return Phi(Region,1.0f,1.2);", stop.toString());
         assertEquals(1.2, Evaluator.evaluate(stop,  0));
     }
 
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index e39fc5d8..e9f8c367 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -11,7 +11,8 @@ public class Chapter18Test {
 
     @Test
     public void testJig() {
-        Parser parser = new Parser("""
+        Parser parser = new Parser(
+"""
 return 3.14;
 """);
         StopNode stop = parser.parse().iterate();
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/TypeTest.java b/chapter18/src/test/java/com/seaofnodes/simple/TypeTest.java
index 61103f54..0fb0d431 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/TypeTest.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/TypeTest.java
@@ -2,7 +2,6 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.type.*;
 import org.junit.Assert;
-import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertSame;
@@ -12,19 +11,24 @@ public class TypeTest {
     // Test basic properties and GLB
     @Test
     public void testTypeAdHoc() {
+        Assert.assertEquals( Type.BOTTOM, TypeInteger.TRUE.meet(TypeNil.NIL) );
+        Assert.assertEquals( Type.BOTTOM, TypeInteger.TOP.meet(TypeNil.NIL) );
+
+
         TypeStruct s1 = TypeStruct.make("s1", new Field[]{
                 Field.make("a", TypeInteger.BOT,-1, false),
                 Field.make("b", TypeInteger.BOT,-2, false) });
         TypeStruct s2 = TypeStruct.make("s2", new Field[]{
                 Field.make("a", TypeInteger.BOT,-3, false),
                 Field.make("b", TypeInteger.BOT,-4, false) });
-        Assert.assertEquals(s1, s1.glb());
+        Assert.assertEquals(s1.makeRO(), s1.glb());
         Assert.assertNotEquals(s1, s1.dual());
         Assert.assertEquals(s1.makeRO(), s1.dual().glb());
 
-        TypeMem m1 = TypeMem.make(1,TypeInteger.ZERO);
+        //TypeMem m1 = TypeMem.make(1,TypeInteger.ZERO);
+        TypeMem m1 = TypeMem.make(1,TypeNil.NIL);
         TypeMem m2 = TypeMem.make(2,TypeInteger.U16);
-        TypeMem m3 = TypeMem.make(3,TypeFloat.BOT);
+        TypeMem m3 = TypeMem.make(3,TypeFloat.F64);
         TypeMem m4 = TypeMem.make(4,TypeInteger.BOT);
 
         Assert.assertNotEquals(m1, m2);
@@ -32,47 +36,50 @@ public class TypeTest {
         Assert.assertNotEquals(m3, m4);
 
         Assert.assertEquals(TypeStruct.BOT, s1.meet(s2));
-        Assert.assertEquals(TypeMem.make(0,TypeInteger.U16), m1.meet(m2));
-        Assert.assertEquals(TypeMem   .BOT, m2.meet(m3));
+        Assert.assertEquals(TypeMem   .BOT, m1.meet(m2));
+        Assert.assertEquals(TypeMem.make(0,TypeFloat.F64), m1.meet(m3));
         Assert.assertEquals(TypeMem   .BOT, m3.meet(m4));
 
-        Assert.assertEquals(TypeMem.make(1,TypeInteger.BOT), m1.glb());
-        Assert.assertEquals(TypeMem.make(1,TypeInteger.ZERO), m1.dual());
+        Assert.assertEquals(m1, m1.glb());
+        //Assert.assertEquals(TypeMem.make(1,TypeInteger.ZERO), m1.dual());
+        Assert.assertEquals(TypeMem.make(1,Type.XNIL), m1.dual());
         Assert.assertEquals(m4.dual(), m4.glb().dual());
 
-        TypeMemPtr ptr1 = TypeMemPtr.make(s1);
+        TypeMemPtr ptr1 = TypeMemPtr.make((byte)2, s1);
         Assert.assertEquals(s1, ptr1._obj);
-        TypeMemPtr ptr2 = TypeMemPtr.make(s2);
+        TypeMemPtr ptr2 = TypeMemPtr.make((byte)2, s2);
         Assert.assertEquals(s2, ptr2._obj);
 
-        TypeMemPtr ptr1nil = TypeMemPtr.make(s1, true);
+        TypeMemPtr ptr1nil = TypeMemPtr.make(s1);
         Assert.assertEquals(s1, ptr1nil._obj);
-        Assert.assertTrue(ptr1nil._nil);
-        Assert.assertFalse(ptr1nil._obj==null);
-        TypeMemPtr ptr2nil = TypeMemPtr.make(s2, true);
+        assertEquals( 3, ptr1nil._nil );
+        Assert.assertNotNull( ptr1nil._obj );
+        TypeMemPtr ptr2nil = TypeMemPtr.make( s2);
         Assert.assertEquals(s2, ptr2nil._obj);
 
         Assert.assertNotEquals(ptr1, ptr2);
         Assert.assertNotEquals(ptr1, ptr1.glb());
-        Assert.assertEquals(ptr1nil, ptr1.glb());
+        Assert.assertEquals(ptr1nil.makeRO(), ptr1.glb());
 
         Assert.assertEquals(ptr1, ptr1.dual().dual());
         Assert.assertEquals(ptr1.glb().makeRO(), ptr1.dual().glb());
-        Assert.assertEquals(TypeMemPtr.make(TypeStruct.BOT,true), ptr1.meet(ptr2nil));
-        Assert.assertEquals(ptr1.glb(), ptr1.meet(TypeMemPtr.NULLPTR));
+        Assert.assertEquals(TypeMemPtr.make((byte)3,TypeStruct.BOT), ptr1.meet(ptr2nil));
+        //Assert.assertEquals(ptr1.glb(), ptr1.meet(TypeMemPtr.NULLPTR));
+        Assert.assertEquals(ptr1.glb(), ptr1.meet(TypeNil.NIL).makeRO());
 
         TypeMemPtr TOP = TypeMemPtr.TOP;
-        TypeMemPtr BOT = TypeMemPtr.make(TypeStruct.BOT,true );
-        TypeMemPtr PTR = TypeMemPtr.make(TypeStruct.BOT,false);
-        TypeMemPtr NULL = TypeMemPtr.NULLPTR;
+        TypeMemPtr BOT = TypeMemPtr.make((byte)3,TypeStruct.BOT);
+        TypeMemPtr PTR = TypeMemPtr.make((byte)2,TypeStruct.BOT);
+        //TypeMemPtr NULL = TypeMemPtr.NULLPTR;
+        Type NULL = TypeNil.NIL;
         Type PTR_meet_NULL = NULL.meet(PTR);
         Assert.assertEquals(BOT, PTR_meet_NULL);
         Type ptr1_meet_ptr2 = ptr1.meet(ptr2);
         Assert.assertEquals(PTR, ptr1_meet_ptr2);
         Type NULL_join_ptr1 = NULL.join(ptr1);
-        Assert.assertEquals(TOP, NULL_join_ptr1);
+        Assert.assertEquals(TypePtr.XNPTR, NULL_join_ptr1);
         Type NULL_join_PTR = PTR.join(NULL);
-        Assert.assertEquals(TOP, NULL_join_PTR);
+        Assert.assertEquals(TypePtr.XNPTR, NULL_join_PTR);
         Type ptr1_dual = ptr1.dual();
         Type nullableptr1_dual = ptr1nil.dual();
     }
@@ -153,5 +160,4 @@ public class TypeTest {
         assertSame(TypeStruct.S1,d1);
     }
 
-
 }
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java b/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
index 72f84fa2..ac442585 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
@@ -263,6 +263,7 @@ public class Evaluator {
     private double vald(Node node) {
         var v = val(node);
         if (v instanceof Number n) return n.doubleValue();
+        if( v == null ) return 0;
         throw new AssertionError("Not a double " + v);
     }
 
@@ -270,7 +271,7 @@ public class Evaluator {
         var type = cons.compute();
         if (type instanceof TypeInteger i) return i.value();
         if (type instanceof TypeFloat i) return i.value();
-        assert type instanceof TypeMemPtr;
+        assert type == Type.NIL;
         return null;
     }
 
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java b/chapter18/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
index 51e39cd0..e86fb7b8 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
@@ -46,8 +46,8 @@ public class Fuzzer {
         e.printStackTrace(System.out);
         System.out.println("========== Seed ==========");
         System.out.println(seed);
-        System.out.println("========== Code ===========");
-        System.out.println(script);
+        //System.out.println("========== Code ===========");
+        //System.out.println(script);
         System.out.println("========= Reduced =========");
         System.out.println(Reducer.reduce(script, e, reproducer));
         System.out.println("===========================");
@@ -63,6 +63,10 @@ public class Fuzzer {
             }
             return false;
         }
+        if( a==null && b == Long.valueOf(0) )
+            return false;
+        if( b==null && a == Long.valueOf(0) )
+            return false;
         return true;
     }
author	Cliff Click <cliffc@acm.org>	2024-12-21 16:43:03 -0800
committer	Cliff Click <cliffc@acm.org>	2025-01-15 15:07:30 -0800
commit	8095c50f846699f7570bdea4c6517653c5795c2e (patch)
tree	1d5ed8477dd796766a3a6aa7b6c5d2e6cb883946 /chapter18
parent	b0b26bd248fad6f6d2ac23f673ae73095cd5c3cb (diff)
download	Simple-8095c50f846699f7570bdea4c6517653c5795c2e.tar.gz Simple-8095c50f846699f7570bdea4c6517653c5795c2e.zip