@@ -8,47 +8,69 @@
 import polemy._common;
 import polemy.failure;
 import polemy.ast;
 import polemy.layer;
+import std.string;
 
 /// Runtime values of Polemy
 
 abstract class Value
 {
+	override bool opEquals(Object rhs) { return 0==opCmp(rhs); }
 }
 
 ///
 class IntValue : Value
 {
 	BigInt data;
 
-	mixin SimpleClass;
-	override string toString() const { return std.bigint.toDecimalString(cast(BigInt)data); }
+	this(int n) { this.data = n; }
+	this(long n) { this.data = n; }
+	this(BigInt n) { this.data = n; }
+	this(string n) { this.data = BigInt(n); }
+	override string toString() const { return toDecimalString(cast(BigInt)data); }
+	override int opCmp(Object rhs) {
+		if(auto r = cast(IntValue)rhs) return data.opCmp(r.data);
+		if(auto r = cast(Value)rhs)    return typeid(this).opCmp(typeid(r));
+		throw genex!RuntimeException(LexPosition.dummy, "comparison with value and somithing other");
+	}
+	mixin SimpleToHash;
 }
 
 ///
 class StrValue : Value
 {
 	string data;
 
-	mixin SimpleClass;
+	mixin SimpleConstructor;
 	override string toString() const { return data; }
+	override int opCmp(Object rhs) {
+		if(auto r = cast(StrValue)rhs) return typeid(string).compare(&data, &r.data);
+		if(auto r = cast(Value)rhs)    return typeid(this).opCmp(typeid(r));
+		throw genex!RuntimeException(LexPosition.dummy, "comparison with value and somithing other");
+	}
+	mixin SimpleToHash;
 }
 
 ///
-class UndValue : Value
+class UndefinedValue : Value
 {
-	mixin SimpleClass;
+	mixin SimpleConstructor;
 	override string toString() const { return "<undefined>"; }
+	override int opCmp(Object rhs) {
+		if(auto r = cast(StrValue)rhs) return 0;
+		if(auto r = cast(Value)rhs)    return typeid(this).opCmp(typeid(r));
+		throw genex!RuntimeException(LexPosition.dummy, "comparison with value and somithing other");
+	}
+	mixin SimpleToHash;
 }
-
 
 ///
 abstract class FunValue : Value
 {
 	const(Parameter[]) params();
 	Table definitionContext();
-	Value invoke(LexPosition pos, Layer lay, Table ctx);
+	Value invoke(Layer lay, Table ctx, LexPosition pos);
 }
 
 /// Context (variable environment)
 /// Simlar to prototype chain of ECMAScript etc.
@@ -337,13 +359,64 @@
 {
 	Table t = new Table;
 	if( pos !is null ) {
 		t.set("filename", ValueLayer, new StrValue(pos.filename));
-		t.set("lineno",   ValueLayer, new IntValue(BigInt(pos.lineno)));
-		t.set("column",   ValueLayer, new IntValue(BigInt(pos.column)));
+		t.set("lineno",   ValueLayer, new IntValue(pos.lineno));
+		t.set("column",   ValueLayer, new IntValue(pos.column));
 	} else {
 		t.set("filename", ValueLayer, new StrValue("nullpos"));
-		t.set("lineno",   ValueLayer, new IntValue(BigInt(0)));
-		t.set("column",   ValueLayer, new IntValue(BigInt(0)));
+		t.set("lineno",   ValueLayer, new IntValue(0));
+		t.set("column",   ValueLayer, new IntValue(0));
 	}
 	return t;
 }
+
+/// Convert AST to Table so that it can be used in Polemy
+/// TODO: generalize to DValue2PolemyValue
+
+Value ast2table(T)(T e, Value delegate(AST) rec)
+{
+	assert( typeid(e) == typeid(T) );
+
+	static if(is(T==BigInt) || is(T==long) || is(T==int))
+		return new IntValue(e);
+	else
+	static if(is(T==string))
+		return new StrValue(e);
+	else
+	static if(is(T S : S[]))
+	{
+		Table lst = new Table;
+		foreach_reverse(a; e)
+			static if(is(S : AST))
+				lst = makeCons(rec(a), lst);
+			else
+				lst = makeCons(ast2table(a,rec), lst);
+		return lst;
+	}
+	else
+	static if(is(T : AST))
+	{
+		auto t = new Table;
+		t.set("pos", ValueLayer, fromPos(e.pos));
+		t.set("is" , ValueLayer, new StrValue(typeid(e).name.split(".")[$-1].tolower()));
+		foreach(i,m; e.tupleof)
+			static if(is(typeof(m) : AST))
+				t.set(e.tupleof[i].stringof[2..$], ValueLayer, rec(m));
+			else
+				t.set(e.tupleof[i].stringof[2..$], ValueLayer, ast2table(m,rec));
+		return t;
+	}
+	else
+	static if(is(T == class))
+	{
+		auto t = new Table;
+		foreach(i,m; e.tupleof)
+			static if(is(typeof(m) : AST))
+				t.set(e.tupleof[i].stringof[2..$], ValueLayer, rec(m));
+			else
+				t.set(e.tupleof[i].stringof[2..$], ValueLayer, ast2table(m,rec));
+		return t;
+	}
+	else
+		static assert(false, "unknown type <"~T.stringof~"> during AST encoding");
+}