@@ -1,5 +1,5 @@
-/**
+/**
  * Authors: k.inaba
  * License: NYSL 0.9982 http://www.kmonos.net/nysl/
  *
  * Evaluator for Polemy programming language.
@@ -12,144 +12,121 @@
 import polemy.value;
 import std.typecons;
 import std.stdio;
 
-Context createGlobalContext()
-{
-	auto ctx = new Context;
-	ctx.add("+", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+Table createGlobalContext()
+{
+	auto ctx = new Table;
+	// [TODO] autogenerate these typechecks
+	ctx.set("+", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		if( args.length != 2 )
-			throw new PolemyRuntimeException("+ takes two arguments!! ["~to!string(pos)~"]");
+			throw new RuntimeException(pos, "+ takes two arguments!!");
 		if( auto x = cast(IntValue)args[0] )
 			if( auto y = cast(IntValue)args[1] )
 				return new IntValue(x.data+y.data);
-		throw new PolemyRuntimeException("cannot add non-integers ["~to!string(pos)~"]");
+		throw new RuntimeException(pos, "cannot add non-integers");
 	}));
-	ctx.add("-", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+	ctx.set("-", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		if( args.length != 2 )
-			throw new PolemyRuntimeException("- takes two arguments!! ["~to!string(pos)~"]");
+			throw new RuntimeException(pos, "- takes two arguments!!");
 		if( auto x = cast(IntValue)args[0] )
 			if( auto y = cast(IntValue)args[1] )
 				return new IntValue(x.data-y.data);
-		throw new PolemyRuntimeException("cannot add non-integers ["~to!string(pos)~"]");
+		throw new RuntimeException(pos, "cannot subtract non-integers");
 	}));
-	ctx.add("*", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+	ctx.set("*", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		if( args.length != 2 )
-			throw new PolemyRuntimeException("* takes two arguments!! ["~to!string(pos)~"]");
+			throw new RuntimeException(pos, "* takes two arguments!!");
 		if( auto x = cast(IntValue)args[0] )
 			if( auto y = cast(IntValue)args[1] )
 				return new IntValue(x.data*y.data);
-		throw new PolemyRuntimeException("cannot add non-integers ["~to!string(pos)~"]");
+		throw new RuntimeException(pos, "cannot multiply non-integers");
 	}));
-	ctx.add("/", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+	ctx.set("/", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		if( args.length != 2 )
-			throw new PolemyRuntimeException("/ takes two arguments!! ["~to!string(pos)~"]");
+			throw new RuntimeException(pos, "/ takes two arguments!!");
 		if( auto x = cast(IntValue)args[0] )
 			if( auto y = cast(IntValue)args[1] )
 				return new IntValue(x.data/y.data);
-		throw new PolemyRuntimeException("cannot add non-integers ["~to!string(pos)~"]");
+		throw new RuntimeException(pos, "cannot divide non-integers");
 	}));
-	ctx.add("<", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+	ctx.set("<", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		if( args.length != 2 )
-			throw new PolemyRuntimeException("< takes two arguments!! ["~to!string(pos)~"]");
+			throw new RuntimeException(pos, "< takes two arguments!!");
 		if( auto x = cast(IntValue)args[0] )
 			if( auto y = cast(IntValue)args[1] )
 				return new IntValue(BigInt(to!int(x.data < y.data)));
-		throw new PolemyRuntimeException("cannot add non-integers ["~to!string(pos)~"]");
+		throw new RuntimeException(pos, "cannot compare non-integers");
 	}));
-	ctx.add(">", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+	ctx.set(">", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		if( args.length != 2 )
-			throw new PolemyRuntimeException("> takes two arguments!! ["~to!string(pos)~"]");
+			throw new RuntimeException(pos, "> takes two arguments!!");
 		if( auto x = cast(IntValue)args[0] )
 			if( auto y = cast(IntValue)args[1] )
 				return new IntValue(BigInt(to!int(x.data>y.data)));
-		throw new PolemyRuntimeException("cannot add non-integers ["~to!string(pos)~"]");
+		throw new RuntimeException(pos, "cannot compare non-integers");
 	}));
-	ctx.add("print", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+	ctx.set("print", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		foreach(a; args)
 			write(a);
 		writeln("");
-		return new UndefinedValue;
+		return new IntValue(BigInt(178));
 	}));
-	ctx.add("if", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
+	ctx.set("if", "@val", new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 		if( args.length != 3 )
-			throw new PolemyRuntimeException("if takes three arguments!! ["~to!string(pos)~"]");
+			throw new RuntimeException(pos, "if takes three arguments!!");
 		if( auto x = cast(IntValue)args[0] )
 		if( auto ft = cast(FunValue)args[1] )
 		if( auto fe = cast(FunValue)args[2] )
 			return (x.data == 0 ? fe : ft).call(pos,[]);
-		throw new PolemyRuntimeException("type mismatch in if ["~to!string(pos)~"]");
+		throw new RuntimeException(pos, "type mismatch in if");
 	}));
 	return ctx;
 }
 
-Tuple!(Value,"val",Context,"ctx") evalString(T...)(T params)
+/// Entry point of this module
+
+Tuple!(Value,"val",Table,"ctx") evalString(S,T...)(S str, T fn_ln_cn)
 {
-	return eval( parserFromString(params).parseProgram() );
+	return eval( polemy.parse.parseString(str, fn_ln_cn) );
 }
 
-Tuple!(Value,"val",Context,"ctx") evalFile(T...)(T params)
+Tuple!(Value,"val",Table,"ctx") evalFile(S, T...)(S filenae, T ln_cn)
 {
-	return eval( parserFromFile(params).parseProgram() );
+	return eval( polemy.parse.parseFile(filename, ln_cn) );
 }
 
-Tuple!(Value,"val",Context,"ctx") eval(Program prog)
+Tuple!(Value,"val",Table,"ctx") eval(AST e)
 {
-	Context ctx = createGlobalContext();
-	return typeof(return)(eval(prog, ctx), ctx);
+	Table ctx = createGlobalContext();
+	return typeof(return)(eval(e, ctx), ctx);
 }
 
-Value eval(Program prog, Context ctx)
-{
-	Value v = new UndefinedValue;
-	foreach(s; prog)
-		v = eval(s, ctx);
-	return v;
-}
-
-Value eval(Statement _s, Context ctx)
+Value eval(AST _e, Table ctx, bool splitCtx = true)
 {
-	if( auto s = cast(DeclStatement)_s )
-	{
-		auto v = eval(s.expr, ctx);
-		ctx.add(s.var, v);
-		return v;
-	}
-	else
-	if( auto s = cast(ExprStatement)_s )
-	{
-		return eval(s.expr, ctx);
-	}
-	throw new PolemyRuntimeException(sprintf!"Unknown Kind of Statement %s at [%s]"(typeid(_s), _s.pos));
-}
-
-Value eval(Expression _e, Context ctx)
-{
-	if( auto e = cast(StrLiteralExpression)_e )
+	if( auto e = cast(StrLiteral)_e )
 	{
 		return new StrValue(e.data);
 	}
 	else
-	if( auto e = cast(IntLiteralExpression)_e )
+	if( auto e = cast(IntLiteral)_e )
 	{
 		return new IntValue(e.data);
 	}
-	else
-	if( auto e = cast(VarExpression)_e )
-	{
-		return ctx[e.var];
-	}
-	else
-	if( auto e = cast(AssignExpression)_e )
-	{
-		if( auto ev = cast(VarExpression)e.lhs )
-		{
-			Value r = eval(e.rhs, ctx);
-			ctx[ev.var] = r;
-			return r;
-		}
-		throw new PolemyRuntimeException(sprintf!"Lhs of assignment must be a variable: %s"(e.pos));
-	}
+	else
+	if( auto e = cast(VarExpression)_e )
+	{
+		return ctx.get(e.var, "@val", e.pos);
+	}
+	else
+	if( auto e = cast(LetExpression)_e )
+	{
+		// for letrec, we need this, but should avoid overwriting????
+		// ctx.set(e.var, "@val", new UndefinedValue, e.pos);
+		Value v = eval(e.init, ctx, true);
+		ctx.set(e.var, "@val", v, e.pos);
+		return eval(e.expr, ctx);
+	}
 	else
 	if( auto e = cast(FuncallExpression)_e )
 	{
 		Value _f = eval(e.fun, ctx);
@@ -158,73 +135,64 @@
 			foreach(a; e.args)
 				args ~= eval(a, ctx);
 			return f.call(e.pos, args);
 		} else
-			throw new PolemyRuntimeException(sprintf!"Non-funcion is applied at [%s]"(e.pos));
+			throw new RuntimeException(e.pos, "Non-funcion is applied");
 	}
 	else
-	if( auto e = cast(FunLiteralExpression)_e )
+	if( auto e = cast(FunLiteral)_e )
 	{
 		return new FunValue(delegate Value(immutable LexPosition pos, Value[] args){
 			if( e.params.length != args.length )
-				throw new PolemyRuntimeException(sprintf!"Argument Number Mismatch (%d required but %d given) at [%s]"
-					(e.params.length, args.length, e.pos));
-			Context ctxNeo = new Context(ctx);
+				throw new RuntimeException(e.pos, sprintf!"Argument Number Mismatch (%d required but %d given)"
+					(e.params.length, args.length));
+			Table ctxNeo = new Table(ctx, Table.Kind.NotPropagateSet);
 			foreach(i,p; e.params)
-				ctxNeo.add(p, args[i]);
+				ctxNeo.set(p, "@val", args[i]);
 			return eval(e.funbody, ctxNeo);
 		});
 	}
-	throw new PolemyRuntimeException(sprintf!"Unknown Kind of Expression %s at [%s]"(typeid(_e), _e.pos));
+	throw new RuntimeException(_e.pos, sprintf!"Unknown Kind of Expression %s"(typeid(_e)));
 }
-
+
 unittest
-{
-	auto r = evalString(`var x = 21; x = x + x*x;`);
-	assert( r.val == new IntValue(BigInt(21+21*21)) );
-	assert( r.ctx["x"] == new IntValue(BigInt(21+21*21)) );
-	assert( !collectException(r.ctx["x"]) );
-	assert( collectException(r.ctx["y"]) );
+{
+	auto r = assert_nothrow( evalString(`var x = 21; x + x*x;`) );
+	assert_eq( r.val, new IntValue(BigInt(21+21*21)) );
+	assert_eq( r.ctx.get("x","@val"), new IntValue(BigInt(21)) );
+	assert_nothrow( r.ctx.get("x","@val") );
+	assert_throw!RuntimeException( r.ctx.get("y","@val") );
 }
+unittest
+{
+	auto r = assert_nothrow( evalString(`var x = 21; var x = x + x*x;`) );
+	assert_eq( r.val, new IntValue(BigInt(21+21*21)) );
+	assert_eq( r.ctx.get("x","@val"), new IntValue(BigInt(21+21*21)) );
+	assert_nothrow( r.ctx.get("x","@val") );
+	assert_throw!RuntimeException( r.ctx.get("y","@val") );
+}
 unittest
 {
-	assert( collectException(evalString(`var x = 21; x = x + x*y;`)) );
-	assert( collectException(evalString(`x=1;`)) );
+	assert_nothrow( evalString(`print("Hello, world!");`) );
+	assert_nothrow( evalString(`print(fun(){});`) );
 }
 unittest
 {
-	auto r = evalString(`var x = fun(a){1+a;}(2);`);
-	assert( r.ctx["x"] == new IntValue(BigInt(3)) );
-	assert( r.val == new IntValue(BigInt(3)) );
-}
-unittest
-{
-	auto r = evalString(`var x = 1; var f = fun(){x=x+1;}; f(); f(); f();`);
-	assert( r.ctx["x"] == new IntValue(BigInt(4)) );
-	assert( r.val == new IntValue(BigInt(4)) );
-}
-unittest
-{
-	evalString(`print("Hello, world!");`);
-	evalString(`print(fun(){});`);
-}
-unittest
-{
-	evalString(`var fac = fun(x){
+	assert_nothrow( evalString(`var fac = fun(x){
 		1;
 	};
-	print(fac(3));`);
-	evalString(`var fac = fun(x){
+	print(fac(3));`));
+	assert_nothrow( evalString(`var fac = fun(x){
 		if(x)
 			{ x*fac(x-1); }
 		else
 			{ 1; };
 	};
-	print(fac(10));`);
-	evalString(`var fib = fun(x){
+	print(fac(10));`));
+	assert_nothrow( evalString(`var fib = fun(x){
 		if(x<2)
 			{ 1; }
 		else
 			{ fib(x-1) + fib(x-2); };
 	};
-	print(fib(10));`);
+	print(fib(10));`));
 }