Made the type checker a tad more robust

analyzer/assignment.go

@@ -129,14 +129,14 @@ func (this *Tree) canAssign (
 		*entity.TypeFloat,
 		*entity.TypeWord:
 
-		if !destination.Equals(source) {
-			return fail()
+		if destination.Equals(source) {
+			return nil
 		}
 
 	default: panic(fmt.Sprint("BUG: analyzer doesnt know about type", destination))
 	}
 
-	return nil
+	return fail()
 }
 
 func (this *Tree) canAssignCoerce (
@@ -181,7 +181,7 @@ func (this *Tree) canAssignCoerce (
 				return fail()
 			}
 		default:
-			if !destination.Equals(source) {
+			if !this.areStructurallyEquivalent(destination, source) {
 				return fail()
 			}
 		}
@@ -189,7 +189,7 @@ func (this *Tree) canAssignCoerce (
 	case *entity.TypeSlice,
 		*entity.TypeArray,
 		*entity.TypeStruct:
-		if !destination.Equals(source) {
+		if !this.areStructurallyEquivalent(destination, source) {
 			return fail()
 		}
 

analyzer/assignment_test.go

@@ -224,9 +224,9 @@ func TestAssignmentInterfaceErrBadLayer (test *testing.T) {
 testStringErr (test,
 "no method named fly defined on this type", 7, 11,
 `
-Bird: ([fly distance:F64] [land])
+Bird: ([fly distance:F64])
 BlueJay: Int
-BlueJay.[land] = { }
+BlueJay.[fly distance:F64] = { }
 BlueJayRef: *BlueJay
 [main] = {
 	b:Bird = a:BlueJayRef
@@ -249,6 +249,17 @@ BlueJay.[land] = { }
 `)
 }
 
+func TestAssignmentErrByteSliceString (test *testing.T) {
+testStringErr (test,
+"expected *:Byte", 4, 13,
+`
+[main] = {
+	a:String = 'hello'
+	b:*:Byte = a
+}
+`)
+}
+
 // TODO: complete and test error cases
 func TestAssignmentPropagateRules (test *testing.T) {
 testString (test,

analyzer/cast_test.go

@@ -84,6 +84,8 @@ IntDerived: Int
 	d:(x:Int y:Int) = (x: 1 y: 2)
 	e:(z:Int a:Int) = [~~ (z:Int a:Int) d]
 	f:Bird = [~~ BlueJay 0]
+	g:String = 'hello'
+	h:*:Byte = [~ *:Byte g]
 }
 `)
 }

analyzer/test-common.go

@@ -31,7 +31,7 @@ func testReaderErr (
 	for index, stream := range inputs {
 		err := ast.Parse(fmt.Sprintf("stream%d.fspl", index), stream)
 		if err != nil {
-			test.Error("parser returned error: ", err)
+			test.Error("parser returned error:", err)
 			return
 		}
 	}
@@ -68,7 +68,7 @@ func testReader (test *testing.T, inputs ...io.Reader) {
 	for index, stream := range inputs {
 		err := ast.Parse(fmt.Sprintf("stream%d.fspl", index), stream)
 		if err != nil {
-			test.Error("parser returned error: ", err)
+			test.Error("parser returned error:", err)
 			return
 		}
 	}
@@ -76,7 +76,7 @@ func testReader (test *testing.T, inputs ...io.Reader) {
 	tree := Tree { }
 	err := tree.Analyze(ast)
 	if err != nil {
-		test.Error("analyzer returned error: ", err)
+		test.Error("analyzer returned error:", err)
 		return
 	}
 }

entity/type.go

@@ -151,7 +151,11 @@ type TypeInt struct {
 }
 func (*TypeInt) ty(){}
 func (this *TypeInt) String () string {
-	return fmt.Sprint("I", this.Width)
+	if this.Signed {
+		return fmt.Sprint("I", this.Width)
+	} else {
+		return fmt.Sprint("U", this.Width)
+	}
 }
 func (this *TypeInt) Equals (ty Type) bool {
 	real, ok := ty.(*TypeInt)