Add Float support

Parsing float constants; float +-*/, auto-widening float expressions.

10 files changed, 421 insertions, 37 deletions

diff --git a/chapter12/src/main/java/com/seaofnodes/simple/.#Parser.java b/chapter12/src/main/java/com/seaofnodes/simple/.#Parser.java
new file mode 100644
index 00000000..57c63c60
--- /dev/null
+++ b/chapter12/src/main/java/com/seaofnodes/simple/.#Parser.java
@@ -0,0 +1 @@
+cliffc@CLIFF-CLICK-LAP.9640:1721544010
\ No newline at end of file
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/Parser.java b/chapter12/src/main/java/com/seaofnodes/simple/Parser.java
index 7e957d9d..6f8e41c6 100644
--- a/chapter12/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter12/src/main/java/com/seaofnodes/simple/Parser.java
@@ -4,6 +4,7 @@ import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.*;
 
 import java.util.*;
+import java.io.ByteArrayInputStream;
 
 /**
  * The Parser converts a Simple source program to the Sea of Nodes intermediate
@@ -158,6 +159,7 @@ public class Parser {
         if( false ) return null;
         else if (matchx("return")  ) return parseReturn();
         else if (matchx("int")     ) return parseDecl(TypeInteger.BOT);
+        else if (matchx("flt")     ) return parseDecl(TypeFloat  .BOT);
         else if (match ("{")       ) return require(parseBlock(),"}");
         else if (matchx("if")      ) return parseIf();
         else if (matchx("while")   ) return parseWhile();
@@ -462,6 +464,8 @@ public class Parser {
             ? new ConstantNode(t.makeInit()).peephole()
             // Assign "= expr;"
             : require(require("=").parseExpression(), ";");
+        if( expr._type instanceof TypeInteger && t instanceof TypeFloat )
+            expr = new ToFloatNode(expr).peephole();
         if( !expr._type.isa(t) )
             throw error("Type " + expr._type.str() + " is not of declared type " + t.str());
         if( _scope.define(name,t,expr) == null )
@@ -490,20 +494,22 @@ public class Parser {
      */
     private Node parseComparison() {
         var lhs = parseAddition();
+        BoolNode op;
         while( true ) {
             int idx=0;  boolean negate=false;
             // Test for any local nodes made, and "keep" lhs during peepholes
             if( false ) ;
-            else if( match("==") ) { idx=2;  lhs = new BoolNode.EQ(lhs, null); }
-            else if( match("!=") ) { idx=2;  lhs = new BoolNode.EQ(lhs, null); negate=true; }
-            else if( match("<=") ) { idx=2;  lhs = new BoolNode.LE(lhs, null); }
-            else if( match("<" ) ) { idx=2;  lhs = new BoolNode.LT(lhs, null); }
-            else if( match(">=") ) { idx=1;  lhs = new BoolNode.LE(null, lhs); }
-            else if( match(">" ) ) { idx=1;  lhs = new BoolNode.LT(null, lhs); }
+            else if( match("==") ) { idx=2;  op = new BoolNode.EQ(lhs, null); }
+            else if( match("!=") ) { idx=2;  op = new BoolNode.EQ(lhs, null); negate=true; }
+            else if( match("<=") ) { idx=2;  op = new BoolNode.LE(lhs, null); }
+            else if( match("<" ) ) { idx=2;  op = new BoolNode.LT(lhs, null); }
+            else if( match(">=") ) { idx=1;  op = new BoolNode.LE(null, lhs); }
+            else if( match(">" ) ) { idx=1;  op = new BoolNode.LT(null, lhs); }
             else break;
             // Peepholes can fire, but lhs is already "hooked", kept alive
-            lhs.setDef(idx,parseAddition());
-            lhs = lhs.peephole();
+            op.setDef(idx,parseAddition());
+            op = op.widen();
+            lhs = op.peephole();
             if( negate )        // Extra negate for !=
                 lhs = new NotNode(lhs).peephole();
         }
@@ -519,13 +525,21 @@ public class Parser {
      * @return an add expression {@link Node}, never {@code null}
      */
     private Node parseAddition() {
-        Node lhs = parseMultiplication();
+        Node lhs = parseMultiplication();  boolean add;
         while( true ) {
-            if( false ) ;
-            else if( match("+") ) lhs = new AddNode(lhs,null);
-            else if( match("-") ) lhs = new SubNode(lhs,null);
+            if( match("+") ) add=true;
+            else if( match("-") ) add=false;
             else break;
-            lhs.setDef(2,parseMultiplication());
+            lhs.keep();
+            var rhs = parseMultiplication();
+            lhs.unkeep();
+            if( lhs._type instanceof TypeFloat || rhs._type instanceof TypeFloat ) {
+                lhs = widen(lhs);
+                rhs = widen(rhs);
+                lhs = add ? new AddFNode(lhs,rhs) : new SubFNode(lhs,rhs);
+            } else {
+                lhs = add ? new AddNode (lhs,rhs) : new SubNode (lhs,rhs);
+            }
             lhs = lhs.peephole();
         }
         return lhs;
@@ -540,18 +554,31 @@ public class Parser {
      * @return a multiply expression {@link Node}, never {@code null}
      */
     private Node parseMultiplication() {
-        var lhs = parseUnary();
+        var lhs = parseUnary();  boolean mul;
         while( true ) {
-            if( false ) ;
-            else if( match("*") ) lhs = new MulNode(lhs,null);
-            else if( match("/") ) lhs = new DivNode(lhs,null);
+            if( match("*") ) mul=true;
+            else if( match("/") ) mul=false;
             else break;
-            lhs.setDef(2,parseUnary());
+            lhs.keep();
+            var rhs = parseUnary();
+            lhs.unkeep();
+            if( lhs._type instanceof TypeFloat || rhs._type instanceof TypeFloat ) {
+                lhs = widen(lhs);
+                rhs = widen(rhs);
+                lhs = mul ? new MulFNode(lhs,rhs) : new DivFNode(lhs,rhs);
+            } else {
+                lhs = mul ? new MulNode (lhs,rhs) : new DivNode (lhs,rhs);
+            }
             lhs = lhs.peephole();
         }
         return lhs;
     }
 
+    // int->float widen
+    public static Node widen(Node x) {
+        return x._type instanceof TypeFloat ? x : new ToFloatNode(x).peephole();
+    }
+
     /**
      * Parse a unary minus expression.
      *
@@ -575,7 +602,7 @@ public class Parser {
      * @return a primary {@link Node}, never {@code null}
      */
     private Node parsePrimary() {
-        if( _lexer.isNumber() ) return parseIntegerLiteral();
+        if( _lexer.isNumber(_lexer.peek()) ) return parseLiteral();
         if( match("(") ) return require(parseExpression(), ")");
         if( matchx("true" ) ) return new ConstantNode(TypeInteger.constant(1)).peephole();
         if( matchx("false") ) return ZERO;
@@ -652,9 +679,10 @@ public class Parser {
      *
      * <pre>
      *     integerLiteral: [1-9][0-9]* | [0]
+     *     floatLiteral: [1-9][0-9]* | [0]
      * </pre>
      */
-    private ConstantNode parseIntegerLiteral() {
+    private ConstantNode parseLiteral() {
         return (ConstantNode) new ConstantNode(_lexer.parseNumber()).peephole();
     }
 
@@ -809,19 +837,36 @@ public class Parser {
             return String.valueOf(peek());
         }
 
-        boolean isNumber() {return isNumber(peek());}
+
         boolean isNumber(char ch) {return Character.isDigit(ch);}
 
         private Type parseNumber() {
-            String snum = parseNumberString();
-            if (snum.length() > 1 && snum.charAt(0) == '0')
-                throw error("Syntax error: integer values cannot start with '0'");
-            return TypeInteger.constant(Long.parseLong(snum));
+            int old = _position;
+            int len = isLongOrDouble();
+            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)));
+            }
+            return TypeFloat.constant(Double.parseDouble(new String(_input,old,-len)));
         }
         private String parseNumberString() {
-            int start = _position;
-            while (isNumber(nextChar())) ;
-            return new String(_input, start, --_position - start);
+            int old = _position;
+            int len = Math.abs(isLongOrDouble());
+            _position += len;
+            return new String(_input,old,len);
+        }
+
+        // Return +len that ends a long
+        // Return -len that ends a double
+        private int isLongOrDouble() {
+            int old = _position;
+            char c;
+            while( Character.isDigit(c=nextChar()) ) ;
+            if( !(c=='e' || c=='.') )
+                return --_position - old;
+            while( Character.isDigit(c=nextChar()) || c=='e' || c=='.' ) ;
+            return -(--_position - old);
         }
 
         // First letter of an identifier
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/node/AddFNode.java b/chapter12/src/main/java/com/seaofnodes/simple/node/AddFNode.java
new file mode 100644
index 00000000..cc416be7
--- /dev/null
+++ b/chapter12/src/main/java/com/seaofnodes/simple/node/AddFNode.java
@@ -0,0 +1,46 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeFloat;
+
+import java.util.BitSet;
+
+public class AddFNode extends Node {
+    public AddFNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+    @Override public String label() { return "AddF"; }
+
+    @Override public String glabel() { return "+"; }
+
+    @Override
+    StringBuilder _print1(StringBuilder sb, BitSet visited) {
+        in(1)._print0(sb.append("("), visited);
+        in(2)._print0(sb.append("+"), visited);
+        return sb.append(")");
+    }
+
+    @Override
+    public Type compute() {
+        if (in(1)._type instanceof TypeFloat i0 &&
+            in(2)._type instanceof TypeFloat i1) {
+            if (i0.isConstant() && i1.isConstant())
+                return TypeFloat.constant(i0.value()+i1.value());
+        }
+        return in(1)._type.meet(in(2)._type);
+    }
+
+    @Override
+    public Node idealize() {
+        Node lhs = in(1);
+        Node rhs = in(2);
+        Type t1 = lhs._type;
+        Type t2 = rhs._type;
+
+        // Add of 1.  
+        if ( t2.isConstant() && t2 instanceof TypeFloat i && i.value()==1 )
+            return lhs;
+
+        return null;
+    }
+    @Override Node copy(Node lhs, Node rhs) { return new AddFNode(lhs,rhs); }
+}
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/chapter12/src/main/java/com/seaofnodes/simple/node/BoolNode.java
index 9c15f01b..1d3a1031 100644
--- a/chapter12/src/main/java/com/seaofnodes/simple/node/BoolNode.java
+++ b/chapter12/src/main/java/com/seaofnodes/simple/node/BoolNode.java
@@ -1,7 +1,10 @@
 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 java.util.BitSet;
@@ -37,7 +40,9 @@ abstract public class BoolNode extends Node {
         return in(1)._type.meet(in(2)._type);
     }
 
-    abstract boolean doOp(long lhs, long rhs);
+    boolean doOp(long   lhs, long   rhs) { throw Utils.TODO(); }
+    boolean doOp(double lhs, double rhs) { throw Utils.TODO(); }
+    BoolNode copyF(Node lhs, Node rhs) { throw Utils.TODO(); }
 
     @Override
     public Node idealize() {
@@ -69,7 +74,19 @@ abstract public class BoolNode extends Node {
         return null;
     }
 
-    public static class EQ extends BoolNode { public EQ(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "=="; } boolean doOp(long lhs, long rhs) { return lhs == rhs; } Node copy(Node lhs, Node rhs) { return new EQ(lhs,rhs); } }
-    public static class LT extends BoolNode { public LT(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<" ; } boolean doOp(long lhs, long rhs) { return lhs <  rhs; } Node copy(Node lhs, Node rhs) { return new LT(lhs,rhs); } }
-    public static class LE extends BoolNode { public LE(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<="; } boolean doOp(long lhs, long rhs) { return lhs <= rhs; } Node copy(Node lhs, Node rhs) { return new LE(lhs,rhs); } }
+    public BoolNode widen() {
+        if( !(in(1)._type instanceof TypeFloat || in(2)._type instanceof TypeFloat) ) return this;
+        Node in1 = Parser.widen(in(1));
+        Node in2 = Parser.widen(in(2));
+        return copyF(in1,in2);
+    }
+
+    public static class EQ extends BoolNode { public EQ(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "=="; } boolean doOp(long lhs, long rhs) { return lhs == rhs; } Node copy(Node lhs, Node rhs) { return new EQ(lhs,rhs); } BoolNode copyF(Node lhs, Node rhs) { return new EQF(lhs,rhs); } }
+    public static class LT extends BoolNode { public LT(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<" ; } boolean doOp(long lhs, long rhs) { return lhs <  rhs; } Node copy(Node lhs, Node rhs) { return new LT(lhs,rhs); } BoolNode copyF(Node lhs, Node rhs) { return new LTF(lhs,rhs); }}
+    public static class LE extends BoolNode { public LE(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<="; } boolean doOp(long lhs, long rhs) { return lhs <= rhs; } Node copy(Node lhs, Node rhs) { return new LE(lhs,rhs); } BoolNode copyF(Node lhs, Node rhs) { return new LEF(lhs,rhs); } }
+
+    public static class EQF extends BoolNode { public EQF(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "=="; } boolean doOp(double lhs, double rhs) { return lhs == rhs; } }
+    public static class LTF extends BoolNode { public LTF(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<" ; } boolean doOp(double lhs, double rhs) { return lhs <  rhs; } }
+    public static class LEF extends BoolNode { public LEF(Node lhs, Node rhs) { super(lhs,rhs); } String op() { return "<="; } boolean doOp(double lhs, double rhs) { return lhs <= rhs; } }
+
 }
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/node/DivFNode.java b/chapter12/src/main/java/com/seaofnodes/simple/node/DivFNode.java
new file mode 100644
index 00000000..3333b417
--- /dev/null
+++ b/chapter12/src/main/java/com/seaofnodes/simple/node/DivFNode.java
@@ -0,0 +1,46 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeFloat;
+
+import java.util.BitSet;
+
+public class DivFNode extends Node {
+    public DivFNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+    @Override public String label() { return "DivF"; }
+
+    @Override public String glabel() { return "*"; }
+
+    @Override
+    StringBuilder _print1(StringBuilder sb, BitSet visited) {
+        in(1)._print0(sb.append("("), visited);
+        in(2)._print0(sb.append("*"), visited);
+        return sb.append(")");
+    }
+
+    @Override
+    public Type compute() {
+        if (in(1)._type instanceof TypeFloat i0 &&
+            in(2)._type instanceof TypeFloat i1) {
+            if (i0.isConstant() && i1.isConstant())
+                return TypeFloat.constant(i0.value()/i1.value());
+        }
+        return in(1)._type.meet(in(2)._type);
+    }
+
+    @Override
+    public Node idealize() {
+        Node lhs = in(1);
+        Node rhs = in(2);
+        Type t1 = lhs._type;
+        Type t2 = rhs._type;
+
+        // Div of 1.  
+        if ( t2.isConstant() && t2 instanceof TypeFloat i && i.value()==1 )
+            return lhs;
+
+        return null;
+    }
+    @Override Node copy(Node lhs, Node rhs) { return new DivFNode(lhs,rhs); }
+}
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/node/MulFNode.java b/chapter12/src/main/java/com/seaofnodes/simple/node/MulFNode.java
new file mode 100644
index 00000000..2d44a9fb
--- /dev/null
+++ b/chapter12/src/main/java/com/seaofnodes/simple/node/MulFNode.java
@@ -0,0 +1,51 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeFloat;
+
+import java.util.BitSet;
+
+public class MulFNode extends Node {
+    public MulFNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+    @Override public String label() { return "MulF"; }
+
+    @Override public String glabel() { return "*"; }
+
+    @Override
+    StringBuilder _print1(StringBuilder sb, BitSet visited) {
+        in(1)._print0(sb.append("("), visited);
+        in(2)._print0(sb.append("*"), visited);
+        return sb.append(")");
+    }
+
+    @Override
+    public Type compute() {
+        if (in(1)._type instanceof TypeFloat i0 &&
+            in(2)._type instanceof TypeFloat i1) {
+            if (i0.isConstant() && i1.isConstant())
+                return TypeFloat.constant(i0.value()*i1.value());
+        }
+        return in(1)._type.meet(in(2)._type);
+    }
+
+    @Override
+    public Node idealize() {
+        Node lhs = in(1);
+        Node rhs = in(2);
+        Type t1 = lhs._type;
+        Type t2 = rhs._type;
+
+        // Mul of 1.  We do not check for (1*x) because this will already
+        // canonicalize to (x*1)
+        if ( t2.isConstant() && t2 instanceof TypeFloat i && i.value()==1 )
+            return lhs;
+
+        // Move constants to RHS: con*arg becomes arg*con
+        if ( t1.isConstant() && !t2.isConstant() )
+            return swap12();
+
+        return null;
+    }
+    @Override Node copy(Node lhs, Node rhs) { return new MulFNode(lhs,rhs); }
+}
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/node/SubFNode.java b/chapter12/src/main/java/com/seaofnodes/simple/node/SubFNode.java
new file mode 100644
index 00000000..aa2553f8
--- /dev/null
+++ b/chapter12/src/main/java/com/seaofnodes/simple/node/SubFNode.java
@@ -0,0 +1,46 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeFloat;
+
+import java.util.BitSet;
+
+public class SubFNode extends Node {
+    public SubFNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
+
+    @Override public String label() { return "SubF"; }
+
+    @Override public String glabel() { return "-"; }
+
+    @Override
+    StringBuilder _print1(StringBuilder sb, BitSet visited) {
+        in(1)._print0(sb.append("("), visited);
+        in(2)._print0(sb.append("-"), visited);
+        return sb.append(")");
+    }
+
+    @Override
+    public Type compute() {
+        if (in(1)._type instanceof TypeFloat i0 &&
+            in(2)._type instanceof TypeFloat i1) {
+            if (i0.isConstant() && i1.isConstant())
+                return TypeFloat.constant(i0.value()-i1.value());
+        }
+        return in(1)._type.meet(in(2)._type);
+    }
+
+    @Override
+    public Node idealize() {
+        Node lhs = in(1);
+        Node rhs = in(2);
+        Type t1 = lhs._type;
+        Type t2 = rhs._type;
+
+        // Sub of 1.  
+        if ( t2.isConstant() && t2 instanceof TypeFloat i && i.value()==1 )
+            return lhs;
+
+        return null;
+    }
+    @Override Node copy(Node lhs, Node rhs) { return new SubFNode(lhs,rhs); }
+}
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java b/chapter12/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
new file mode 100644
index 00000000..1d147cf6
--- /dev/null
+++ b/chapter12/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
@@ -0,0 +1,30 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeFloat;
+import com.seaofnodes.simple.type.TypeInteger;
+
+import java.util.BitSet;
+
+public class ToFloatNode extends Node {
+    public ToFloatNode(Node lhs) { super(null, lhs); }
+
+    @Override public String label() { return "ToFloat"; }
+
+    @Override public String glabel() { return "(flt)"; }
+
+    @Override
+    StringBuilder _print1(StringBuilder sb, BitSet visited) {
+        return in(1)._print0(sb.append("(flt)"), visited);
+    }
+
+    @Override
+    public Type compute() {
+        if (in(1)._type instanceof TypeInteger i0 && i0.isConstant() )
+            return TypeFloat.constant(i0.value());
+        return TypeFloat.BOT;
+    }
+
+    @Override public Node idealize() { return null; }
+    @Override Node copy(Node lhs, Node rhs) { return new ToFloatNode(lhs); }
+}
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/type/Type.java b/chapter12/src/main/java/com/seaofnodes/simple/type/Type.java
index aa0ba1ea..f3152719 100644
--- a/chapter12/src/main/java/com/seaofnodes/simple/type/Type.java
+++ b/chapter12/src/main/java/com/seaofnodes/simple/type/Type.java
@@ -33,11 +33,12 @@ public class Type {
     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 TTUPLE  = 6; // Tuples; finite collections of unrelated Types, kept in parallel
-    static final byte TMEM    = 7; // All memory (alias 0) or A slice of memory - with specific alias
-    static final byte TMEMPTR = 8; // Memory pointer type
-    static final byte TSTRUCT = 9; // Structs; tuples with named fields
-    static final byte TFLD    =10; // Fields into struct
+    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
 
     public final byte _type;
 
diff --git a/chapter12/src/main/java/com/seaofnodes/simple/type/TypeFloat.java b/chapter12/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
new file mode 100644
index 00000000..36bc61f5
--- /dev/null
+++ b/chapter12/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
@@ -0,0 +1,101 @@
+package com.seaofnodes.simple.type;
+
+import java.util.ArrayList;
+
+/**
+ * Float Type
+ */
+public class TypeFloat extends Type {
+
+    public final static TypeFloat TOP = make(false, 0);
+    public final static TypeFloat BOT = make(false, 1);
+    public final static TypeFloat ZERO= make(true , 0);
+
+    public final boolean _is_con;
+
+    /**
+     * The constant value or
+     * if not constant then 1=bottom, 0=top.
+     */
+    public final double _con;
+
+    private TypeFloat(boolean is_con, double con) {
+        super(TFLT);
+        _is_con = is_con;
+        _con = con;
+    }
+    public static TypeFloat make(boolean is_con, double con) {
+        return new TypeFloat(is_con,con).intern();
+    }
+
+    public static TypeFloat constant(double con) { return make(true, con); }
+
+    public static void gather(ArrayList<Type> ts) { ts.add(ZERO); ts.add(BOT); }
+
+    // FIXME this display format is problematic
+    // In visualizer '#' gets prepended if its a constant
+    @Override
+    public StringBuilder _print(StringBuilder sb) {
+        if( this==TOP ) return sb.append("FltTop");
+        if( this==BOT ) return sb.append("FltBot");
+        return sb.append(_con);
+    }
+
+    @Override public String str() {
+        if( this==TOP ) return "~flt";
+        if( this==BOT ) return  "flt";
+        return ""+_con;
+    }
+
+    /**
+     * Display Type name in a format that's good for IR printer
+     */
+    @Override
+    public StringBuilder typeName(StringBuilder sb) {
+        if( this==TOP ) return sb.append("FltTop");
+        if( this==BOT ) return sb.append("FltBot");
+        return sb.append("Int");
+    }
+
+    @Override
+    public boolean isHighOrConst() { return _is_con || _con==0; }
+
+    @Override
+    public boolean isConstant() { return _is_con; }
+
+    public double value() { return _con; }
+
+    @Override
+    public Type xmeet(Type other) {
+        // Invariant from caller: 'this' != 'other' and same class (TypeFloat)
+        TypeFloat i = (TypeFloat)other; // Contract
+        // BOT wins
+        if ( this==BOT ) return this;
+        if ( i   ==BOT ) return i   ;
+        // TOP loses
+        if ( i   ==TOP ) return this;
+        if ( this==TOP ) return i   ;
+        // Since both are constants, and are never equals (contract) unequals
+        // constants fall to bottom
+        return BOT;
+    }
+
+    @Override
+    public Type dual() {
+        if( isConstant() ) return this; // Constants are a self-dual
+        return _con==0 ? BOT : TOP;
+    }
+
+    @Override
+    public Type glb() { return BOT; }
+
+    @Override public TypeFloat makeInit() { return ZERO; }
+
+    @Override
+    int hash() { return (int)(Double.hashCode(_con) ^ (_is_con ? 0 : 0x4000)); }
+    @Override
+    public boolean eq( Type t ) {
+        TypeFloat i = (TypeFloat)t; // Contract
+        return _con==i._con && _is_con==i._is_con;
+    }
+}