From 2f2d18567f31f5d2de2668bf26e9b81809ba2a1d Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Sun, 27 Apr 2025 14:51:23 -0700
Subject: Mid hack

---
 .../main/java/com/seaofnodes/simple/Parser.java    | 205 ++++++++++++---------
 .../src/main/java/com/seaofnodes/simple/Var.java   |  21 ++-
 .../com/seaofnodes/simple/node/ExternNode.java     |  26 +++
 .../main/java/com/seaofnodes/simple/node/Node.java |   8 +-
 .../java/com/seaofnodes/simple/node/ScopeNode.java |  89 ++++++---
 .../main/java/com/seaofnodes/simple/sys/sys.java   |  25 +++
 .../main/java/com/seaofnodes/simple/sys/sys.smp    |  10 +
 .../java/com/seaofnodes/simple/Chapter22Test.java  |   1 -
 .../src/test/java/com/seaofnodes/simple/Eval2.java |   3 +-
 .../seaofnodes/simple/fuzzer/ScriptGenerator.java  |   2 +-
 .../com/seaofnodes/simple/progs/helloWorld.smp     |   2 +
 11 files changed, 272 insertions(+), 120 deletions(-)
 create mode 100644 chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java
 create mode 100644 chapter22/src/main/java/com/seaofnodes/simple/sys/sys.java
 create mode 100644 chapter22/src/main/java/com/seaofnodes/simple/sys/sys.smp
 create mode 100644 chapter22/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp

diff --git a/chapter22/src/main/java/com/seaofnodes/simple/Parser.java b/chapter22/src/main/java/com/seaofnodes/simple/Parser.java
index d7f5087d..d44ea46e 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/Parser.java
@@ -4,7 +4,7 @@ import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.print.GraphVisualizer;
 import com.seaofnodes.simple.type.*;
-import java.text.ParseException;
+
 import java.util.*;
 
 /**
@@ -81,31 +81,11 @@ public class Parser {
     ScopeNode _breakScope;      // Merge all the while-breaks here
     FunNode _fun;               // Current function being parsed
 
-    // Mapping from a type name to a Type.  The string name matches
+    // Mapping from a primitive name to a Type.  The string name matches
     // `type.str()` call.  No TypeMemPtrs are in here, because Simple does not
     // have C-style '*ptr' references.
-    public static HashMap<String, Type> TYPES;
-
-    // Mapping from a type name to the constructor for a Type.
-    public final HashMap<String, StructNode> INITS;
-
-
-    public Parser(CodeGen code, TypeInteger arg) {
-        _code = code;
-        _scope = new ScopeNode();
-        _continueScope = _breakScope = null;
-        ZERO  = con(TypeInteger.ZERO).keep();
-        NIL  = con(Type.NIL).keep();
-        XCTRL= new XCtrlNode().peephole().keep();
-        TYPES = defaultTypes();
-        INITS = new HashMap<>();
-    }
-
-    @Override
-    public String toString() { return _lexer.toString(); }
-
-    public static HashMap<String, Type> defaultTypes() {
-        return new HashMap<>() {{
+    public static final HashMap<String, Type> PRIMS =
+        new HashMap<>() {{
             put("bool",TypeInteger.U1 );
             put("byte",TypeInteger.U8 );
             put("f32" ,TypeFloat  .F32);
@@ -123,8 +103,25 @@ public class Parser {
             put("val" ,Type.TOP);    // Marker type, indicates type inference
             put("var" ,Type.BOTTOM); // Marker type, indicates type inference
         }};
+
+
+    // Mapping from a type name to the constructor for a Type.
+    public final HashMap<String, StructNode> INITS;
+
+
+    public Parser(CodeGen code, TypeInteger arg) {
+        _code = code;
+        _scope = new ScopeNode();
+        _continueScope = _breakScope = null;
+        ZERO  = con(TypeInteger.ZERO).keep();
+        NIL  = con(Type.NIL).keep();
+        XCTRL= new XCtrlNode().peephole().keep();
+        INITS = new HashMap<>();
     }
 
+    @Override
+    public String toString() { return _lexer.toString(); }
+
     // Debugging utility to find a Node by index
     public Node f(int nid) { return _code.f(nid); }
 
@@ -132,19 +129,32 @@ public class Parser {
     private <N extends Node> N ctrl(N n) { return _scope.ctrl(n); }
 
     public void parse() {
+        _scope.define(ScopeNode.CTRL, Type.CONTROL   , false, null, null);
+        _scope.define(ScopeNode.MEM0, TypeMem.BOT    , false, null, null);
+        _scope.define(ScopeNode.ARG0, TypeInteger.BOT, false, null, null);
+
+        ctrl(XCTRL);
+        _scope.mem(new MemMergeNode(false));
+
+        // Parse the "sys" import
         //_parse(com.seaofnodes.simple.sys.sys.SYS);
+
+        _code._stop.popUntil(0); // Delete return from parsing sys import
+
+        // Parse program text
         _parse(_code._src);
+
+        // Clean up and reset
+        _scope.kill();
+        for( StructNode init : INITS.values() )
+            init.unkeep().kill();
+        INITS.clear();
+        _code._stop.peephole();
     }
 
     private void _parse(String src) {
         _lexer = new Lexer(src);
         _xScopes.push(_scope);
-        _scope.define(ScopeNode.CTRL, Type.CONTROL   , false, null, _lexer);
-        _scope.define(ScopeNode.MEM0, TypeMem.BOT    , false, null, _lexer);
-        _scope.define(ScopeNode.ARG0, TypeInteger.BOT, false, null, _lexer);
-
-        ctrl(XCTRL);
-        _scope.mem(new MemMergeNode(false));
 
         // Parse whole program, as-if function header "{ int arg -> body }"
         parseFunctionBody(_code._main,loc(),"arg");
@@ -172,11 +182,6 @@ public class Parser {
 
         // Clean up and reset
         _xScopes.pop();
-        _scope.kill();
-        for( StructNode init : INITS.values() )
-            init.unkeep().kill();
-        INITS.clear();
-        stop.peephole();
     }
 
     /**
@@ -212,7 +217,7 @@ public class Parser {
         // Pre-call the function from Start, with worse-case arguments.  This
         // represents all the future, yet-to-be-parsed functions calls and
         // external calls.
-        _scope.push(ScopeNode.Kind.Function);
+        _scope.push(ScopeNode.Kind.Function,null);
         ctrl(fun);              // Scope control from function
         // Private mem alias tracking per function
         MemMergeNode mem = new MemMergeNode(true);
@@ -271,7 +276,7 @@ public class Parser {
      */
     private Node parseBlock(ScopeNode.Kind kind) {
         // Enter a new scope
-        _scope.push(kind);
+        _scope.push(kind,null);
         Node last = ZERO;
         while (!peek('}') && !_lexer.isEOF())
             last = parseStatement();
@@ -290,8 +295,7 @@ public class Parser {
      * @return a {@link Node} or {@code null}
      */
     private Node parseStatement() {
-        if( false ) return null;
-        else if (matchx("return")  ) return parseReturn();
+        if(      matchx("return")  ) return parseReturn();
         else if (matchx("if")      ) return parseIf();
         else if (matchx("while")   ) return parseWhile();
         else if (matchx("for")     ) return parseFor();
@@ -339,7 +343,7 @@ public class Parser {
         //     }
         // }
         require("(");
-        _scope.push(ScopeNode.Kind.Block); // Scope for the index variables
+        _scope.push(ScopeNode.Kind.Block,null); // Scope for the index variables
         if( !match(";") )       // Can be empty init "for(;test;next) body"
             parseDeclarationStatement(); // Non-empty init
         Node rez = parseLooping(true);
@@ -406,7 +410,7 @@ public class Parser {
         // Our current scope is the body Scope
         ctrl(ifT.unkeep());     // set ctrl token to ifTrue projection
         _scope.addGuards(ifT,pred.unkeep(),false); // Up-cast predicate
-        parseStatement();       // Parse loop body
+        parseStatement().isKill();                 // Parse loop body
         _scope.removeGuards(ifT);
 
         // Merge the loop bottom into other continue statements
@@ -631,7 +635,7 @@ public class Parser {
         // outside the constructor need to check the final bit.
         if( _scope.in(def._idx)._type!=Type.TOP && def._final &&
             // Inside a constructor, final assign is OK, outside nope
-            !(_scope.inCon() && def._idx >= _scope._lexSize.last()) )
+            !(_scope.inConstructor() && def._idx >= _scope._lexSize.last()) )
             throw error("Cannot reassign final '"+name+"'");
 
         // Lift expression, based on type
@@ -673,9 +677,17 @@ public class Parser {
      * exprAsgn = var '=' exprAsgn | expr
      */
     private Node parseDeclarationStatement() {
+        int old = pos();
         Type t = type();
         if( t == null )
             return require(parseAsgn(),";");
+        // Ambiguous leading type then doing a type/class static field lookup.
+        // "T var" - declare a variable of type T
+        // "T.fld" - lookup field "fld" in type T
+        if( peek('.') ) {
+            pos(old);
+            return require(parseAsgn(),";");
+        }
 
         // now parse var['=' asgnexpr] in a loop
         Node n = parseDeclaration(t);
@@ -717,14 +729,17 @@ public class Parser {
                 t = expr._type;
                 if( !xfinal ) t = t.glb();  // Widen if not final
             }
-            if( t instanceof TypeFunPtr && expr._type instanceof TypeFunPtr tfp && tfp.isConstant() )
-                _code.link(tfp)._name = name;
+            // expr is a constant function
+            if( t instanceof TypeFunPtr && expr._type instanceof TypeFunPtr tfp && tfp.isConstant() ) {
+                if( expr instanceof ExternNode ) t = expr._type; // Upgrade declared type to exact function
+                else _code.link(tfp)._name = name; // Assign debug name to Simple function
+            }
 
         } else {
             // Need an expression to infer the type.
             // Also, if not-null then need an initializing expression.
             // Allowed in a class def, because type/init will happen in the constructor.
-            if( (inferType || (t instanceof TypeNil tn && !tn.nullable() )) && !_scope.inCon() )
+            if( (inferType || (t instanceof TypeNil tn && !tn.nullable() )) && !_scope.inDeclarationQ() )
                 throw errorSyntax("=expression");
             // Initial value for uninitialized struct fields.
             expr = switch( t ) {
@@ -759,44 +774,61 @@ public class Parser {
 
     /**
      * Parse a struct declaration, and return the following statement.
-     * Only allowed in top level scope.
-     * Structs cannot be redefined.
+     * Structs cannot be redefined, but can be nested.
      *
-     * @return The statement following the struct
+     * @return zero
      */
     private Node parseStruct() {
         if (_xScopes.size() > 1) throw error("struct declarations can only appear in top level scope");
+        // "struct" already parsed, so expect the struct name next.
         String typeName = requireId();
-        Type t = TYPES.get(typeName);
-        if( t!=null && !(t instanceof TypeMemPtr tmp && tmp.isFRef() ) )
-            throw error("struct '" + typeName + "' cannot be redefined");
 
         // A Block scope parse, and inspect the scope afterward for fields.
-        _scope.push(ScopeNode.Kind.Constructor);
+        _scope.push(ScopeNode.Kind.DeclarationQ,typeName);
         require("{");
         while (!peek('}') && !_lexer.isEOF())
-            parseStatement();
+            parseStatement().isKill();
 
         // Grab the declarations and build fields and a Struct
         int lexlen = _scope._lexSize.last();
         int varlen = _scope._vars._len;
-        StructNode s = new StructNode();
-        Ary<Field> fs = new Ary<>(Field.class);
+        StructNode inst = new StructNode();
+        StructNode clz  = new StructNode();
+        Ary<Field> fs = new Ary<>(Field.class); // Struct fields
+        Ary<Field> cs = new Ary<>(Field.class); // Class  fields
         for( int i=lexlen; i<varlen; i++ ) {
-            Var v = _scope._vars.at(i);
-            if( !v.isFRef() ) { // Promote to outer scope, not defined here
-                s.addDef(_scope.in(i));
-                fs.push( Field.make( v._name, v.type(), _code.getALIAS(), v._final ) );
-            }
+            Var v = _scope.var(i);
+            if( v.isFRef() )  continue; // Promote to outer scope, not defined here
+            var flds = v._final && v.type().isConstant() ? cs : fs;
+            var stru = v._final && v.type().isConstant() ? clz : inst;
+            // Declare field, gather field init
+            flds.push(Field.make(v._name,v.type(),_code.getALIAS(),v._final));
+            stru.addDef(_scope.in(i));
         }
         TypeStruct ts = s._ts = TypeStruct.make(typeName, fs.asAry());
-        TYPES.put(typeName, TypeMemPtr.make(ts));
+        //PRIMS.put(typeName, TypeMemPtr.make(ts));
         INITS.put(typeName,s.peephole().keep());
+
+        //String clzName = typeName + ".clz";     // Class name
+        //PRIMS.put(clzName, TypeMemPtr.make(TypeStruct.make(clzName, cs.asAry())));
         // Done with struct/block scope
         require("}");
         require(";");
         _scope.pop();
-        return ZERO;
+        // Make a pointer to the class fields
+
+        // ISSUE: LOOKUP EXPECTS TO FIND INSTANCE FIELDS FOR 'NEW' OR TYPE DECLS:
+        // Vector2D v = ...;
+        // Type for 'v' includes fields 'x,y'.
+        // Whereas: Vector2D.PI lookups up via the class struct.
+        // So e.g. add a hidden " decl" field that gets the instance fields.
+        cs.push(Field.make(" decl",TypeMemPtr.make(ts),-1,true));
+
+        TypeMemPtr tclz = TypeMemPtr.make(TypeStruct.make(typeName, cs.asAry()));
+        ConstantNode nclz = con(tclz);
+        // Define the constant clazz fields
+        _scope.define(typeName,tclz, true, nclz, true, loc());
+        return nclz;
     }
 
 
@@ -815,13 +847,15 @@ public class Parser {
         String tname = _lexer.matchId();
         if( tname==null ) return null;
 
-        // Convert the type name to a type.
-        Type t0 = TYPES.get(tname);
+        // Convert the type name to a type, either user instance type or a primitive.
+        Type t0 = _scope.lookupInstance(tname);
+        if( t0 == null ) t0 = PRIMS.get(tname);
         // No new types as keywords
         if( t0 == null && KEYWORDS.contains(tname) )
             return posT(old1);
         if( t0 == Type.BOTTOM || t0 == Type.TOP ) return t0; // var/val type inference
-        Type t1 = t0 == null ? TypeMemPtr.make(TypeStruct.makeFRef(tname)) :t0; // Null: assume a forward ref type
+        // Still no type found?  Assume forward reference
+        Type t1 = t0 == null ? TypeMemPtr.make(TypeStruct.makeFRef(tname)) : t0; // Null: assume a forward ref type
         // Nest arrays and '?' as needed
         Type t2 = t1;
         while( true ) {
@@ -843,13 +877,12 @@ public class Parser {
         int old2 = pos();
         match("!");
         String id = _lexer.matchId();
-        if( !(peek(',') || peek(';') || match("->")) )
-            return posT(old1);
-        pos(old2);              // Reset lexer to reparse
-        if( id==null )
+        if( !(peek(',') || peek(';') || match("->")) || id==null )
             return posT(old1);  // Reset lexer to reparse
+        pos(old2);              // Reset lexer to reparse
         // Yes a forward ref, so declare it
-        TYPES.put(tname,t1);
+        _scope.define(tname, t1, true, XCTRL, true, null);
+        // Return the (array, final) type
         return t2;
     }
 
@@ -858,14 +891,15 @@ public class Parser {
         if( t instanceof TypeMemPtr tmp && tmp.notNull()  )
             throw error("Arrays of reference types must always be nullable");
         String tname = "["+t.str()+"]";
-        Type ta = TYPES.get(tname);
+        Type ta = PRIMS.get(tname);
         if( ta != null ) return (TypeMemPtr)ta;
         // Need make an array type.
         TypeStruct ts = TypeStruct.makeAry(TypeInteger.U32,_code.getALIAS(),t,_code.getALIAS());
         assert ts.str().equals(tname);
         TypeMemPtr tary = TypeMemPtr.make(ts);
-        TYPES.put(tname,tary);
-        return tary;
+        //PRIMS.put(tname,tary);
+        //return tary;
+        throw Utils.TODO();
     }
 
     // A function type is `{ type... -> type }` or `{ type }`.
@@ -1183,7 +1217,7 @@ public class Parser {
         if( hasConstructor ) {
             idx = _scope.nIns();
             // Push a scope, and pre-assign all struct fields.
-            _scope.push(ScopeNode.Kind.Block);
+            _scope.push(ScopeNode.Kind.Block,null);
             Lexer loc = loc();
             for( int i=0; i<fs.length; i++ )
                 _scope.define(fs[i]._fname, fs[i]._type, fs[i]._final, s.in(i)._type==Type.TOP ? con(Type.BOTTOM) : s.in(i), loc);
@@ -1282,18 +1316,24 @@ public class Parser {
             throw error( "Expected "+(name=="#" || name=="[]" ? "array" : "reference")+" but found " + 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 + "'");
-        TypeStruct base = tmp._obj;
+        // Find the field from the Type.  Lookup in the base object field names.
+        TypeStruct base = ptr._obj;
+        if( base.isFRef() ) {
+            //ptr = _scope.lookupInstance(base._name);
+            //base = ptr._obj;
+            throw Utils.TODO();
+        }
         int fidx = base.find(name);
-        if( fidx == -1 ) throw error("Accessing unknown field '" + name + "' from '" + ptr.str() + "'");
+        if( fidx == -1 ) { // No such field!
+            throw error("Accessing unknown field '" + name + "' from '" + ptr.str() + "'");
+            // TODO: ch22 allow class field lookups
+        }
 
         // Get field type and layout offset from base type and field index fidx
         Field f = base._fields[fidx];  // Field from field index
         Type tf = f._type;
         if( tf instanceof TypeMemPtr ftmp && ftmp.isFRef() )
-            tf = ftmp.makeFrom(((TypeMemPtr)(TYPES.get(ftmp._obj._name)))._obj);
+            tf = ftmp.makeFrom(((TypeMemPtr)(PRIMS.get(ftmp._obj._name)))._obj);
 
         // Field offset; fixed for structs, computed for arrays
         Node off = (name.equals("[]")       // If field is an array body
@@ -1453,8 +1493,9 @@ public class Parser {
     }
     // External linked constant
     private Node externDecl( String ex, Type t ) {
-        //return new ExternNode(t,ex).peephole();
-        throw Utils.TODO();
+        if( t instanceof TypeFunPtr tfp )          // Generic TFP from type parse
+            t  = _code.makeFun(tfp._sig,tfp._ret); // Get a FIDX, becomes a constant
+        return new ExternNode(t,ex).peephole();
     }
 
     /**
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/Var.java b/chapter22/src/main/java/com/seaofnodes/simple/Var.java
index e71d7ef2..154b99f4 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/Var.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/Var.java
@@ -9,28 +9,33 @@ import com.seaofnodes.simple.type.*;
 public class Var {
 
     public final String _name;   // Declared name
+    // These fields are not final for forward reference late updates or
+    // promotions.
     public int _idx;             // index in containing scope
     private Type _type;          // Declared type
     public boolean _final;       // Final field
-    public Parser.Lexer _loc;    // Source location
     public boolean _fref;        // Forward ref
+    public final boolean _clz;   // Is a Simple clazz
+    public Parser.Lexer _loc;    // Source location
 
     public Var(int idx, String name, Type type, boolean xfinal, Parser.Lexer loc ) {
-        this(idx,name,type,xfinal,loc,false);
+        this(idx,name,type,xfinal,loc,false,false);
     }
-    public Var(int idx, String name, Type type, boolean xfinal, Parser.Lexer loc, boolean fref) {
+    public Var(int idx, String name, Type type, boolean xfinal, Parser.Lexer loc, boolean clz, boolean fref) {
         _idx = idx;
         _name = name;
         _type = type;
         _final = xfinal;
-        _loc = loc;
         _fref = fref;
+        _clz  = clz;
+        _loc = loc;
     }
     public Type type() {
         if( !_type.isFRef() ) return _type;
         // Update self to no longer use the forward ref type
-        Type def = Parser.TYPES.get(((TypeMemPtr)_type)._obj._name);
-        return (_type=_type.meet(def));
+        //Type def = Parser.TYPES.get(((TypeMemPtr)_type)._obj._name);
+        //return (_type=_type.meet(def));
+        throw Utils.TODO();
     }
     public Type lazyGLB() {
         Type t = type();
@@ -45,11 +50,11 @@ public class Var {
         assert isFRef() && xfinal;
         _type = type;
         _final = true;
-        _loc = loc;
         _fref = false;
+        _loc = loc;
     }
 
     @Override public String toString() {
-        return _type.toString()+(_final ? " ": " !")+_name;
+        return _type.toString()+(_final ? " ": " !")+(_clz?"@":"")+_name;
     }
 }
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java b/chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java
new file mode 100644
index 00000000..3c3701c7
--- /dev/null
+++ b/chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java
@@ -0,0 +1,26 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.Parser;
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeFunPtr;
+import java.util.BitSet;
+
+/**
+   A constant with external linkage.
+ */
+
+public class ExternNode extends ConstantNode {
+    public final String _extern;
+    public ExternNode(Type t, String ex) { super(t); _extern = ex; }
+
+    @Override public String  label() { return "#"+_con+":"+_extern; }
+    @Override public String glabel() { return _con.gprint(new SB().p("#")).p(":").p(_extern).toString(); }
+    @Override public String uniqueName() { return "Extern_" + _nid; }
+
+    @Override public boolean eq(Node n) { return this==n; }
+
+    @Override int hash() { return _con.hashCode(); }
+
+}
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter22/src/main/java/com/seaofnodes/simple/node/Node.java
index c0c2e606..18a8bc14 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -239,7 +239,7 @@ public abstract class Node implements Cloneable {
 
     // Shortcut for "popping" until n nodes.  A "pop" is basically a
     // setDef(last,null) followed by lowering the nIns() count.
-    void popUntil(int n) {
+    public void popUntil(int n) {
         unlock();
         while( nIns() > n ) {
             Node old_def = _inputs.pop();
@@ -255,9 +255,9 @@ public abstract class Node implements Cloneable {
      * code elimination.
      */
     public void kill( ) {
+        assert isUnused();      // Has no uses, so it is dead
         unlock();
         moveDepsToWorklist();
-        assert isUnused();      // Has no uses, so it is dead
         _type=null;             // Flag as dead
         while( nIns()>0 ) { // Set all inputs to null, recursively killing unused Nodes
             Node old_def = _inputs.removeLast();
@@ -295,6 +295,10 @@ public abstract class Node implements Cloneable {
         if( unkeep().isUnused() )
             kill();
     }
+    public void isKill() {
+        if( isUnused() )
+            kill();
+    }
 
 
     // Replace self with nnn in the graph, making 'this' go dead
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/chapter22/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
index 38a5d968..eda29915 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -25,9 +25,15 @@ public class ScopeNode extends MemMergeNode {
     // Size of each nested lexical scope
     public final Ary<Integer> _lexSize;
 
-    // Lexical scope is one of normal Block, constructor or function
-    public enum Kind { Block, Constructor, Function };
+    // Lexical scope is typed:
+    // - Block scope - basic block scoping
+    // - Constructor - struct type is defined, and here we give values to all fields
+    // - Declaration - struct is declared, final constant fields defined
+    // - Function - out-of-scope lookups restricted to final constants
+    public enum Kind { Block, Constructor, DeclarationQ, Function };
     public final Ary<Kind> _kinds;
+    // Each Constructor scope is named, allowing for nested Type names
+    public final Ary<String> _tnamesQ;
 
     // Extra guards; tested predicates and casted results
     private final Ary<Node> _guards;
@@ -38,6 +44,7 @@ public class ScopeNode extends MemMergeNode {
         _vars   = new Ary<>(Var    .class);
         _lexSize= new Ary<>(Integer.class);
         _kinds  = new Ary<>(Kind   .class);
+        _tnamesQ = new Ary<>(String .class);
         _guards = new Ary<>(Node   .class);
     }
 
@@ -49,7 +56,7 @@ public class ScopeNode extends MemMergeNode {
         int j=1;
         for( int i=0; i<nIns(); i++ ) {
             if( j < _lexSize._len && i == _lexSize.at(j) ) { sb.append("| "); j++; }
-            Var v = _vars.get(i);
+            Var v = _vars.at(i);
             sb.append(v.type().print(new SB()));
             sb.append(" ");
             if( v._final ) sb.append("!");
@@ -71,6 +78,7 @@ public class ScopeNode extends MemMergeNode {
 
     public Node ctrl() { return in(0); }
     public MemMergeNode mem() { return (MemMergeNode)in(1); }
+    public Var var(int i) { return _vars.at(i); }
 
     /**
      * The ctrl of a ScopeNode is always bound to the currently active
@@ -85,20 +93,23 @@ public class ScopeNode extends MemMergeNode {
     public <N extends Node> N ctrl(N n) { return setDef(0,n); }
     public Node mem(Node n) { return setDef(1,n); }
 
-    public void push(Kind kind) {
-        assert _lexSize._len==_kinds._len;
+    public void push(Kind kind, String tnameQ) {
+        assert _lexSize._len==_kinds._len && _lexSize._len==_tnamesQ._len;
+        assert !(kind==Kind.DeclarationQ && tnameQ==null);
         _lexSize.push(_vars.size());
         _kinds  .push(kind);
+        _tnamesQ .push(tnameQ);
     }
 
     // Pop a lexical scope
     public void pop() {
-        assert _lexSize._len==_kinds._len;
-        promote();
+        assert _lexSize._len==_kinds._len && _lexSize._len==_tnamesQ._len;
+        promote();              // Promote forward references to the next outer scope
         int n = _lexSize.pop();
         _kinds.pop();
-        popUntil(n);
-        _vars.setLen(n);
+        _tnamesQ.pop();
+        popUntil(n);            // Pop off inputs going out of scope
+        _vars.setLen(n);        // Pop off variables going out of scope
     }
 
 
@@ -107,7 +118,7 @@ public class ScopeNode extends MemMergeNode {
     public void promote() {
         int n = _lexSize.last();
         for( int i=n; i<nIns(); i++ ) {
-            Var v = _vars.at(i);
+            Var v = var(i);
             if( !v.isFRef() ) continue;
             if( _lexSize._len==1 )
                 throw Parser.error("Undefined name '" + v._name + "'",v._loc);
@@ -120,7 +131,15 @@ public class ScopeNode extends MemMergeNode {
     }
 
 
-    public boolean inCon() { return _kinds.last() == Kind.Constructor; }
+    public boolean inConstructor() { return _kinds.last() == Kind.Constructor; }
+    public boolean inDeclarationQ() { return _kinds.last() == Kind.DeclarationQ; }
+    // Nearest enclosing declaration scope name
+    public String declNameQ() {
+        for( int i=_lexSize._len-1; i>=0; i-- )
+            if( _kinds.at(i)==Kind.DeclarationQ )
+                return _tnamesQ.at(i);
+        return null;
+    }
 
     // Is v outside any current function scope?
     public boolean outOfFunction( Var v ) {
@@ -134,9 +153,9 @@ public class ScopeNode extends MemMergeNode {
     // Find name in reverse, return an index into _vars or -1.  Linear scan
     // instead of hashtable, but probably doesn't matter until the scan
     // typically hits many dozens of variables.
-    int find( String name ) {
+    public int find( String name, boolean clz ) {
         for( int i=_vars.size()-1; i>=0; i-- )
-            if( _vars.at(i)._name.equals(name) )
+            if( var(i)._name.equals(name) && var(i)._clz==clz )
                 return i;
         return -1;
     }
@@ -145,10 +164,13 @@ public class ScopeNode extends MemMergeNode {
      * Create a new variable name in the current scope
      */
     public boolean define( String name, Type declaredType, boolean xfinal, Node init, Parser.Lexer loc ) {
+        return define(name,declaredType,xfinal,init,false,loc);
+    }
+    public boolean define( String name, Type declaredType, boolean xfinal, Node init, boolean clz, Parser.Lexer loc ) {
         assert _lexSize.isEmpty() || name.charAt(0)!='$' ; // Later scopes do not define memory
         if( _lexSize._len > 0 )
             for( int i=_vars.size()-1; i>=_lexSize.last(); i-- ) {
-                Var n = _vars.at(i);
+                Var n = var(i);
                 if( n._name.equals(name) ) {
                     if( !n.isFRef() ) return false;       // Double define
                     FRefNode fref = (FRefNode)in(n._idx); // Get forward ref
@@ -157,7 +179,7 @@ public class ScopeNode extends MemMergeNode {
                     setDef(n._idx,fref.addDef(init));     // Set FRef to defined; tell parser also
                 }
             }
-        Var v = new Var(nIns(),name,declaredType,xfinal,loc,init==Parser.XCTRL);
+        Var v = new Var(nIns(),name,declaredType,xfinal,loc,clz,init==Parser.XCTRL);
         _vars.add(v);
         // Creating a forward reference
         if( init==Parser.XCTRL )
@@ -179,21 +201,37 @@ public class ScopeNode extends MemMergeNode {
      * @return null if not found, or the implementing Node
      */
     public Var lookup( String name ) {
-        int idx = find(name);
+        int idx = find(name,false);
+        // -1 is missed in all scopes, not found
+        return idx == -1 ? null : update(var(idx),null);
+    }
+
+    /**
+     * Lookup a type name and return the instance TypeMemPtr
+     *
+     * @param name of Type
+     * @return null if not found, or *instance* TypeMemPtr
+     */
+    public TypeMemPtr lookupInstance( String name ) {
+        int idx = find(name,true);
         // -1 is missed in all scopes, not found
-        return idx == -1 ? null : update(_vars.at(idx),null);
+        if( idx == -1 ) return null;
+        // Class types are always TMPs
+        TypeMemPtr clz = (TypeMemPtr)var(idx).type();
+        // Instance types are always TMPs
+        return (TypeMemPtr)(clz._obj.field(" decl")._type);
     }
 
     /**
-     * If the name is present in any scope, then redefine else null
+     * Redefine an existing name
      *
      * @param name Name being redefined
      * @param n    The node to bind to the name
      */
     public void update( String name, Node n ) {
-        int idx = find(name);
+        int idx = find(name,false);
         assert idx>=0;
-        update(_vars.at(idx),n);
+        update(var(idx),n);
     }
 
     public Var update( Var v, Node st ) {
@@ -238,6 +276,7 @@ public class ScopeNode extends MemMergeNode {
         dup._vars   .addAll(_vars   );
         dup._lexSize.addAll(_lexSize);
         dup._kinds  .addAll(_kinds  );
+        dup._tnamesQ .addAll(_tnamesQ );
         dup._guards .addAll(_guards );
         // The dup'd guards all need dup'd keepers, to keep proper accounting
         // when later removing all guards
@@ -260,7 +299,7 @@ public class ScopeNode extends MemMergeNode {
         for( int i=2; i<nIns(); i++ )
             // For lazy phis on loops we use a sentinel
             // that will trigger phi creation on update
-            dup.addDef(loop && !_vars.at(i)._final ? this : in(i));
+            dup.addDef(loop && !var(i)._final ? this : in(i));
         return dup;
     }
 
@@ -286,7 +325,7 @@ public class ScopeNode extends MemMergeNode {
             if( in(i) != that.in(i) ) { // No need for redundant Phis
                 // If we are in lazy phi mode we need to a lookup
                 // by name as it will trigger a phi creation
-                Var v = _vars.at(i);
+                Var v = var(i);
                 Node lhs = this.in(this.update(v,null));
                 Node rhs = that.in(that.update(v,null));
                 setDef(i, new PhiNode(v._name, v.type(), r, lhs, rhs).peephole());
@@ -297,7 +336,7 @@ public class ScopeNode extends MemMergeNode {
     // Forward refs are copied to the other side, "as if" they were there all along.
     public void balanceIf( ScopeNode scope ) {
         for( int i = nIns(); i < scope.nIns(); i++ ) {
-            Var n = scope._vars.at(i);
+            Var n = scope.var(i);
             if( n.isFRef() ) {  // RHS has forward refs
                 _vars.add(n);   // Copy to LHS
                 addDef(scope.in(i));
@@ -329,8 +368,8 @@ public class ScopeNode extends MemMergeNode {
     // Fill in the backedge of any inserted Phis
     void _endLoop( ScopeNode scope, Node back, Node exit ) {
         for( int i=2; i<nIns(); i++ ) {
-            if( _vars.at(i)._final ) continue; // Final vars did not get modified in the loop
-            if( _vars.at(i).type().isHighOrConst() ) continue; // Cannot lift higher than a constant, so no Phi
+            if( var(i)._final ) continue; // Final vars did not get modified in the loop
+            if( var(i).type().isHighOrConst() ) continue; // Cannot lift higher than a constant, so no Phi
             if( back.in(i) != scope ) {
                 PhiNode phi = (PhiNode)in(i);
                 assert phi.region()==scope.ctrl() && phi.in(2)==null;
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/sys/sys.java b/chapter22/src/main/java/com/seaofnodes/simple/sys/sys.java
new file mode 100644
index 00000000..399e7cb7
--- /dev/null
+++ b/chapter22/src/main/java/com/seaofnodes/simple/sys/sys.java
@@ -0,0 +1,25 @@
+package com.seaofnodes.simple.sys;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+
+/** Default included namespaces for Simple.
+
+    You can think of this as {@code #include <stdio.h>} for C or {@code import java.lang.*} for Java.
+ */
+public abstract class sys {
+
+    public static final String SYS;
+
+    static {
+        try {
+            SYS = Files.readString(Path.of("src/main/java/com/seaofnodes/simple/sys/sys.smp"));
+        }
+        catch( Exception e ) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/sys/sys.smp b/chapter22/src/main/java/com/seaofnodes/simple/sys/sys.smp
new file mode 100644
index 00000000..8c470716
--- /dev/null
+++ b/chapter22/src/main/java/com/seaofnodes/simple/sys/sys.smp
@@ -0,0 +1,10 @@
+// -*- mode: java;  -*-
+
+// top-level default import
+struct sys {
+    // libc bindings
+    struct libc {
+        /** https://www.man7.org/linux/man-pages/man2/write.2.html */
+        { i32 u8[] i32 -> i32 } write = "C";
+    };
+};
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java b/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
index 106932f5..dccf00bc 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
@@ -28,7 +28,6 @@ public class Chapter22Test {
             assertEquals(stop, code._stop.toString());
     }
 
-
     @Test
     public void testCoRecur() {
         String src = """
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/Eval2.java b/chapter22/src/test/java/com/seaofnodes/simple/Eval2.java
index ecea97dd..38da6898 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/Eval2.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/Eval2.java
@@ -407,7 +407,8 @@ public abstract class Eval2 {
             // Since never can close the type cycle, without cyclic types, have
             // to handle FRefs even here
             if( tmp.isFRef() )
-                tmp = tmp.makeFrom(((TypeMemPtr)Parser.TYPES.get(tmp._obj._name))._obj);
+                //tmp = tmp.makeFrom(((TypeMemPtr)Parser.TYPES.get(tmp._obj._name))._obj);
+                throw Utils.TODO();
 
             Object[] xs = (Object[])x; // Array of fields
             if( tmp._obj.isAry() ) {
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java b/chapter22/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
index f119fa1a..c9f7d801 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
@@ -97,7 +97,7 @@ public class ScriptGenerator {
     private static final List<TypeInt> INTTYPES = new ArrayList<>();
 
     static {
-        for( var e : Parser.defaultTypes().entrySet() ) {
+        for( var e : Parser.PRIMS.entrySet() ) {
             if( e.getValue() instanceof TypeInteger ) {
                 INTTYPES.add(new TypeInt(e.getKey()));
             }
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp
new file mode 100644
index 00000000..0234aa73
--- /dev/null
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp
@@ -0,0 +1,2 @@
+// -*- mode: java;  -*-
+sys.libc.write(1,"Hello, World!\n",14);
-- 
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