Fix a few flubs

* Add a TODO as a reminder to implement number toString formatting.

* Change the Loreley delimiters to something obscure ("<{%" and "%}>")
  to avoid conflicting with actual characters we might use in messages.
  Also, make the assertions more descriptive should Loreley fail.

* Rip out a debug.PrintStack() in verbose logging.

* Check the underlying pointer's object type for +=, not the pointer type.

lib/mujs/runtime/ecmascript.ts

@@ -20,6 +20,8 @@ export function toString(argument: Object): string {
         return "false";
     }
     if (isNumber(argument)) {
+        // TODO: implement number formatting.
+        return "NaN";
     }
     if (isSymbol(argument)) {
         throw new TypeError();

pkg/diag/sink.go

@@ -106,6 +106,19 @@ func (d *defaultSink) Warningf(diag *Diag, args ...interface{}) {
 	d.warnings++
 }
 
+const colorLeft = "<{%"
+const colorRight = "%}>"
+
+func init() {
+	// Change the Loreley delimiters from { and }, to something more complex, to avoid accidental collisions.
+	loreley.DelimLeft = colorLeft
+	loreley.DelimRight = colorRight
+}
+
+func colorString(s string) string {
+	return colorLeft + s + colorRight
+}
+
 func (d *defaultSink) Stringify(diag *Diag, cat Category, args ...interface{}) string {
 	var buffer bytes.Buffer
 
@@ -119,9 +132,9 @@ func (d *defaultSink) Stringify(diag *Diag, cat Category, args ...interface{}) s
 	if d.opts.Colors {
 		switch cat {
 		case Error:
-			buffer.WriteString("{fg 1}") // red
+			buffer.WriteString(colorString("fg 1")) // red
 		case Warning:
-			buffer.WriteString("{fg 11}") // bright yellow
+			buffer.WriteString(colorString("fg 11")) // bright yellow
 		default:
 			contract.Failf("Unrecognized diagnostic category: %v", cat)
 		}
@@ -138,18 +151,18 @@ func (d *defaultSink) Stringify(diag *Diag, cat Category, args ...interface{}) s
 	buffer.WriteString(": ")
 
 	if d.opts.Colors {
-		buffer.WriteString("{reset}")
+		buffer.WriteString(colorString("reset"))
 	}
 
 	// Finally, actually print the message itself.
 	if d.opts.Colors {
-		buffer.WriteString("{fg 7}") // white
+		buffer.WriteString(colorString("fg 7")) // white
 	}
 
 	buffer.WriteString(fmt.Sprintf(diag.Message, args...))
 
 	if d.opts.Colors {
-		buffer.WriteString("{reset}")
+		buffer.WriteString(colorString("reset"))
 	}
 
 	buffer.WriteRune('\n')
@@ -163,7 +176,7 @@ func (d *defaultSink) Stringify(diag *Diag, cat Category, args ...interface{}) s
 	if d.opts.Colors {
 		var err error
 		s, err = loreley.CompileAndExecuteToString(s, nil, nil)
-		contract.Assert(err == nil)
+		contract.Assertf(err == nil, "Expected no errors during string format operation; str=%v, err=%v", s, err)
 	}
 
 	return s
@@ -174,7 +187,7 @@ func (d *defaultSink) StringifyLocation(doc *Document, loc *Location) string {
 
 	if doc != nil {
 		if d.opts.Colors {
-			buffer.WriteString("{fg 6}") // cyan
+			buffer.WriteString(colorString("fg 6")) // cyan
 		}
 
 		file := doc.File
@@ -199,7 +212,7 @@ func (d *defaultSink) StringifyLocation(doc *Document, loc *Location) string {
 	var s string
 	if doc != nil || loc != nil {
 		if d.opts.Colors {
-			buffer.WriteString("{reset}")
+			buffer.WriteString(colorString("reset"))
 		}
 
 		s = buffer.String()
@@ -208,7 +221,7 @@ func (d *defaultSink) StringifyLocation(doc *Document, loc *Location) string {
 		if d.opts.Colors {
 			var err error
 			s, err = loreley.CompileAndExecuteToString(s, nil, nil)
-			contract.Assert(err == nil)
+			contract.Assertf(err == nil, "Expected no errors during string format operation; str=%v, err=%v", s, err)
 		}
 	}
 

pkg/eval/eval.go

@@ -5,7 +5,6 @@ package eval
 import (
 	"math"
 	"reflect"
-	"runtime/debug"
 	"sort"
 	"strconv"
 
@@ -569,7 +568,7 @@ func (e *evaluator) evalCall(node diag.Diagable, fnc symbols.Function,
 	if uw != nil {
 		if uw.Throw() {
 			if glog.V(7) {
-				glog.V(7).Infof("Evaluated call to fnc %v; unhandled exception: %v", uw.Exception().Thrown)
+				glog.V(7).Infof("Evaluated call to fnc %v; unhandled exception: %v", fnc, uw.Exception().Thrown)
 			}
 			return nil, uw
 		}
@@ -654,6 +653,9 @@ func (e *evaluator) evalLocalVariableDeclaration(node *ast.LocalVariableDeclarat
 	if node.Local.Default != nil {
 		obj := e.alloc.NewConstant(*node.Local.Default)
 		e.locals.SetValue(sym, obj)
+		if e.hooks != nil {
+			e.hooks.OnVariableAssign(nil, tokens.Name(sym.Name()), nil, obj)
+		}
 	}
 
 	return nil
@@ -807,7 +809,6 @@ func (e *evaluator) evalExpressionStatement(node *ast.ExpressionStatement) *rt.U
 func (e *evaluator) evalExpression(node ast.Expression) (*rt.Object, *rt.Unwind) {
 	if glog.V(7) {
 		glog.V(7).Infof("Evaluating expression: %v", reflect.TypeOf(node))
-		debug.PrintStack()
 	}
 
 	// Simply switch on the node type and dispatch to the specific function, returning the object and rt.Unwind info.
@@ -1479,7 +1480,7 @@ func (e *evaluator) evalBinaryOperatorExpression(node *ast.BinaryOperatorExpress
 	case ast.OpAssignSum:
 		var val *rt.Object
 		ptr := lhs.PointerValue()
-		if lhs.Type() == types.String {
+		if ptr.Obj().Type() == types.String {
 			// If the lhs/rhs are strings, just concatenate += and yield the new value as a result.
 			val = e.alloc.NewString(ptr.Obj().StringValue() + rhs.StringValue())
 		} else {