Refactor Type to be an int

internal/ast/ast.go

@@ -41,7 +41,7 @@ func (p *Program) String() string {
 	var s strings.Builder
 
 	for _, stmt := range p.Statements {
-		s.WriteString(fmt.Sprintf("%s\n", stmt.String()))
+		s.WriteString(stmt.String())
 	}
 
 	return s.String()

internal/builtins/abs.go

@@ -10,7 +10,7 @@ func Abs(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"abs", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/accept.go

@@ -11,7 +11,7 @@ func Accept(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"accept", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/assert.go

@@ -12,7 +12,7 @@ func Assert(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"assert", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.BOOLEAN_OBJ, object.STRING_OBJ),
+		typing.WithTypes(object.BooleanType, object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/bin.go

@@ -12,7 +12,7 @@ func Bin(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"bin", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/bind.go

@@ -11,7 +11,7 @@ func Bind(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"bind", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType, object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/chr.go

@@ -11,7 +11,7 @@ func Chr(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"chr", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/close.go

@@ -11,7 +11,7 @@ func Close(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"close", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/connect.go

@@ -11,7 +11,7 @@ func Connect(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"connect", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.INTEGER_OBJ, object.STRING_OBJ),
+		typing.WithTypes(object.IntegerType, object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/divmod.go

@@ -10,7 +10,7 @@ func Divmod(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"divmod", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType, object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/exit.go

@@ -10,7 +10,7 @@ func Exit(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"exit", args,
 		typing.RangeOfArgs(0, 1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/ffi.go

@@ -15,7 +15,7 @@ func FFI(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"ffi", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.STRING_OBJ, object.STRING_OBJ),
+		typing.WithTypes(object.StringType, object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/find.go

@@ -23,7 +23,7 @@ func Find(args ...object.Object) object.Object {
 	if haystack, ok := args[0].(*object.String); ok {
 		if err := typing.Check(
 			"find", args,
-			typing.WithTypes(object.STRING_OBJ, object.STRING_OBJ),
+			typing.WithTypes(object.StringType, object.StringType),
 		); err != nil {
 			return newError(err.Error())
 		}
@@ -46,7 +46,7 @@ func Find(args ...object.Object) object.Object {
 	}
 
 	return newError(
-		"TypeError: find() expected argument #1 to be `array` or `str` got `%s`",
+		"TypeError: find() expected argument #1 to be `array` or `str` got `%d`",
 		args[0].Type(),
 	)
 }

internal/builtins/first.go

@@ -10,7 +10,7 @@ func First(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"first", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/hex.go

@@ -12,7 +12,7 @@ func Hex(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"hex", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/input.go

@@ -14,7 +14,7 @@ func Input(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"input", args,
 		typing.RangeOfArgs(0, 1),
-		typing.WithTypes(object.STRING_OBJ),
+		typing.WithTypes(object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/join.go

@@ -11,7 +11,7 @@ func Join(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"join", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.ARRAY_OBJ, object.STRING_OBJ),
+		typing.WithTypes(object.ArrayType, object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/last.go

@@ -10,7 +10,7 @@ func Last(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"last", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/listen.go

@@ -11,7 +11,7 @@ func Listen(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"listen", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType, object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/lower.go

@@ -11,7 +11,7 @@ func Lower(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"lower", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.STRING_OBJ),
+		typing.WithTypes(object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/max.go

@@ -11,7 +11,7 @@ func Max(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"max", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}
@@ -23,7 +23,7 @@ func Max(args ...object.Object) object.Object {
 		if i, ok := e.(*object.Integer); ok {
 			xs = append(xs, int(i.Value))
 		} else {
-			return newError("item #%d  not an `int` got=%s", n, e.Type())
+			return newError("item #%d  not an `int` got=%d", n, e.Type())
 		}
 	}
 	sort.Ints(xs)

internal/builtins/min.go

@@ -11,7 +11,7 @@ func Min(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"min", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}
@@ -23,7 +23,7 @@ func Min(args ...object.Object) object.Object {
 		if i, ok := e.(*object.Integer); ok {
 			xs = append(xs, int(i.Value))
 		} else {
-			return newError("item #%d  not an `int` got=%s", n, e.Type())
+			return newError("item #%d  not an `int` got=%d", n, e.Type())
 		}
 	}
 	sort.Ints(xs)

internal/builtins/oct.go

@@ -12,7 +12,7 @@ func Oct(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"oct", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/open.go

@@ -55,7 +55,7 @@ func Open(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"open", args,
 		typing.RangeOfArgs(1, 2),
-		typing.WithTypes(object.STRING_OBJ, object.STRING_OBJ),
+		typing.WithTypes(object.StringType, object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/ord.go

@@ -10,7 +10,7 @@ func Ord(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"ord", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.STRING_OBJ),
+		typing.WithTypes(object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/pop.go

@@ -10,7 +10,7 @@ func Pop(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"pop", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/pow.go

@@ -22,7 +22,7 @@ func Pow(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"pow", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType, object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/print.go

@@ -11,7 +11,7 @@ func Print(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"print", args,
 		typing.MinimumArgs(1),
-		typing.WithTypes(object.STRING_OBJ),
+		typing.WithTypes(object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/push.go

@@ -10,7 +10,7 @@ func Push(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"push", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/read.go

@@ -14,7 +14,7 @@ func Read(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"read", args,
 		typing.RangeOfArgs(1, 2),
-		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType, object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/readfile.go

@@ -11,7 +11,7 @@ func ReadFile(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"readfile", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.STRING_OBJ),
+		typing.WithTypes(object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/rest.go

@@ -10,7 +10,7 @@ func Rest(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"rest", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/reversed.go

@@ -10,7 +10,7 @@ func Reversed(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"reversed", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/seek.go

@@ -11,7 +11,7 @@ func Seek(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"seek", args,
 		typing.RangeOfArgs(1, 3),
-		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ, object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType, object.IntegerType, object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/socket.go

@@ -12,7 +12,7 @@ func Socket(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"socket", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.STRING_OBJ),
+		typing.WithTypes(object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/sorted.go

@@ -11,7 +11,7 @@ func Sorted(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"sort", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.ARRAY_OBJ),
+		typing.WithTypes(object.ArrayType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/split.go

@@ -11,7 +11,7 @@ func Split(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"split", args,
 		typing.RangeOfArgs(1, 2),
-		typing.WithTypes(object.STRING_OBJ, object.STRING_OBJ),
+		typing.WithTypes(object.StringType, object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/typeof.go

@@ -14,5 +14,5 @@ func TypeOf(args ...object.Object) object.Object {
 		return newError(err.Error())
 	}
 
-	return &object.String{Value: string(args[0].Type())}
+	return &object.String{Value: args[0].Type().String()}
 }

internal/builtins/upper.go

@@ -11,7 +11,7 @@ func Upper(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"upper", args,
 		typing.ExactArgs(1),
-		typing.WithTypes(object.STRING_OBJ),
+		typing.WithTypes(object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/write.go

@@ -11,7 +11,7 @@ func Write(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"write", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ),
+		typing.WithTypes(object.IntegerType, object.IntegerType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/builtins/writefile.go

@@ -11,7 +11,7 @@ func WriteFile(args ...object.Object) object.Object {
 	if err := typing.Check(
 		"writefile", args,
 		typing.ExactArgs(2),
-		typing.WithTypes(object.STRING_OBJ, object.STRING_OBJ),
+		typing.WithTypes(object.StringType, object.StringType),
 	); err != nil {
 		return newError(err.Error())
 	}

internal/compiler/bytecode.go

@@ -67,8 +67,7 @@ func (e *encoder) WriteValue(data any) error {
 
 func (e *encoder) WriteObjects(objs ...object.Object) (err error) {
 	for _, obj := range objs {
-		err = errors.Join(err, e.WriteValue(len(string(obj.Type()))))
-		err = errors.Join(err, e.WriteString(string(obj.Type())))
+		err = errors.Join(err, e.WriteValue(obj.Type()))
 
 		switch o := obj.(type) {
 		case *object.Null:
@@ -145,16 +144,16 @@ func (d *decoder) String(len int) (s string) {
 
 func (d *decoder) Objects(len int) (o []object.Object) {
 	for i := 0; i < len; i++ {
-		switch t := d.String(d.Int()); t {
-		case object.NULL_OBJ:
+		switch t := object.Type(d.Int()); t {
+		case object.NullType:
 			o = append(o, &object.Null{})
-		case object.BOOLEAN_OBJ:
+		case object.BooleanType:
 			o = append(o, &object.Boolean{Value: d.Byte() == 1})
-		case object.INTEGER_OBJ:
+		case object.IntegerType:
 			o = append(o, &object.Integer{Value: d.Int64()})
-		case object.STRING_OBJ:
+		case object.StringType:
 			o = append(o, &object.String{Value: d.String(d.Int())})
-		case object.COMPILED_FUNCTION_OBJ:
+		case object.CFunctionType:
 			// The order of the fields has to reflect the data layout in the encoded bytecode.
 			o = append(o, &object.CompiledFunction{
 				NumParameters: d.Int(),
@@ -162,7 +161,7 @@ func (d *decoder) Objects(len int) (o []object.Object) {
 				Instructions:  d.Bytes(d.Int()),
 			})
 		default:
-			panic(fmt.Sprintf("decoder: unsupported decoding for type %s", t))
+			panic(fmt.Sprintf("decoder: unsupported decoding for type %d", t))
 		}
 	}
 	return

internal/evaluator/evaluator.go

@@ -20,7 +20,7 @@ var (
 
 func isError(obj object.Object) bool {
 	if obj != nil {
-		return obj.Type() == object.ERROR_OBJ
+		return obj.Type() == object.ErrorType
 	}
 	return false
 }
@@ -262,7 +262,7 @@ func evalBlockStatements(block *ast.BlockStatement, env *object.Environment) obj
 
 		if result != nil {
 			rt := result.Type()
-			if rt == object.RETURN_VALUE_OBJ || rt == object.ERROR_OBJ {
+			if rt == object.ReturnType || rt == object.ErrorType {
 				return result
 			}
 		}
@@ -281,7 +281,7 @@ func nativeBoolToBooleanObject(input bool) object.Object {
 func evalPrefixExpression(operator string, right object.Object) object.Object {
 	switch operator {
 	case "!":
-		if right.Type() == object.BOOLEAN_OBJ {
+		if right.Type() == object.BooleanType {
 			return evalBooleanPrefixOperatorExpression(operator, right)
 		}
 		return evalIntegerPrefixOperatorExpression(operator, right)
@@ -293,7 +293,7 @@ func evalPrefixExpression(operator string, right object.Object) object.Object {
 }
 
 func evalBooleanPrefixOperatorExpression(operator string, right object.Object) object.Object {
-	if right.Type() != object.BOOLEAN_OBJ {
+	if right.Type() != object.BooleanType {
 		return newError("unknown operator: %s%s", operator, right.Type())
 	}
 
@@ -310,7 +310,7 @@ func evalBooleanPrefixOperatorExpression(operator string, right object.Object) o
 }
 
 func evalIntegerPrefixOperatorExpression(operator string, right object.Object) object.Object {
-	if right.Type() != object.INTEGER_OBJ {
+	if right.Type() != object.IntegerType {
 		return newError("unknown operator: -%s", right.Type())
 	}
 
@@ -331,7 +331,7 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 	switch {
 
 	// {"a": 1} + {"b": 2}
-	case operator == "+" && left.Type() == object.HASH_OBJ && right.Type() == object.HASH_OBJ:
+	case operator == "+" && left.Type() == object.HashType && right.Type() == object.HashType:
 		leftVal := left.(*object.Hash).Pairs
 		rightVal := right.(*object.Hash).Pairs
 		pairs := make(map[object.HashKey]object.HashPair)
@@ -344,7 +344,7 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 		return &object.Hash{Pairs: pairs}
 
 	// [1] + [2]
-	case operator == "+" && left.Type() == object.ARRAY_OBJ && right.Type() == object.ARRAY_OBJ:
+	case operator == "+" && left.Type() == object.ArrayType && right.Type() == object.ArrayType:
 		leftVal := left.(*object.Array).Elements
 		rightVal := right.(*object.Array).Elements
 		elements := make([]object.Object, len(leftVal)+len(rightVal))
@@ -352,7 +352,7 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 		return &object.Array{Elements: elements}
 
 	// [1] * 3
-	case operator == "*" && left.Type() == object.ARRAY_OBJ && right.Type() == object.INTEGER_OBJ:
+	case operator == "*" && left.Type() == object.ArrayType && right.Type() == object.IntegerType:
 		leftVal := left.(*object.Array).Elements
 		rightVal := int(right.(*object.Integer).Value)
 		elements := leftVal
@@ -362,7 +362,7 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 		return &object.Array{Elements: elements}
 
 	// 3 * [1]
-	case operator == "*" && left.Type() == object.INTEGER_OBJ && right.Type() == object.ARRAY_OBJ:
+	case operator == "*" && left.Type() == object.IntegerType && right.Type() == object.ArrayType:
 		leftVal := int(left.(*object.Integer).Value)
 		rightVal := right.(*object.Array).Elements
 		elements := rightVal
@@ -372,13 +372,13 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 		return &object.Array{Elements: elements}
 
 	// " " * 4
-	case operator == "*" && left.Type() == object.STRING_OBJ && right.Type() == object.INTEGER_OBJ:
+	case operator == "*" && left.Type() == object.StringType && right.Type() == object.IntegerType:
 		leftVal := left.(*object.String).Value
 		rightVal := right.(*object.Integer).Value
 		return &object.String{Value: strings.Repeat(leftVal, int(rightVal))}
 
 	// 4 * " "
-	case operator == "*" && left.Type() == object.INTEGER_OBJ && right.Type() == object.STRING_OBJ:
+	case operator == "*" && left.Type() == object.IntegerType && right.Type() == object.StringType:
 		leftVal := left.(*object.Integer).Value
 		rightVal := right.(*object.String).Value
 		return &object.String{Value: strings.Repeat(rightVal, int(leftVal))}
@@ -396,11 +396,11 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 	case operator == ">":
 		return nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) == 1)
 
-	case left.Type() == object.BOOLEAN_OBJ && right.Type() == object.BOOLEAN_OBJ:
+	case left.Type() == object.BooleanType && right.Type() == object.BooleanType:
 		return evalBooleanInfixExpression(operator, left, right)
-	case left.Type() == object.INTEGER_OBJ && right.Type() == object.INTEGER_OBJ:
+	case left.Type() == object.IntegerType && right.Type() == object.IntegerType:
 		return evalIntegerInfixExpression(operator, left, right)
-	case left.Type() == object.STRING_OBJ && right.Type() == object.STRING_OBJ:
+	case left.Type() == object.StringType && right.Type() == object.StringType:
 		return evalStringInfixExpression(operator, left, right)
 
 	default:
@@ -597,13 +597,13 @@ func unwrapReturnValue(obj object.Object) object.Object {
 
 func evalIndexExpression(left, index object.Object) object.Object {
 	switch {
-	case left.Type() == object.STRING_OBJ && index.Type() == object.INTEGER_OBJ:
+	case left.Type() == object.StringType && index.Type() == object.IntegerType:
 		return evalStringIndexExpression(left, index)
-	case left.Type() == object.ARRAY_OBJ && index.Type() == object.INTEGER_OBJ:
+	case left.Type() == object.ArrayType && index.Type() == object.IntegerType:
 		return evalArrayIndexExpression(left, index)
-	case left.Type() == object.HASH_OBJ:
+	case left.Type() == object.HashType:
 		return evalHashIndexExpression(left, index)
-	case left.Type() == object.MODULE_OBJ:
+	case left.Type() == object.ModuleType:
 		return EvalModuleIndexExpression(left, index)
 	default:
 		return newError("index operator not supported: %s", left.Type())

internal/object/array.go

@@ -10,8 +10,8 @@ type Array struct {
 	Elements []Object
 }
 
-func (ao *Array) Type() ObjectType {
-	return ARRAY_OBJ
+func (ao *Array) Type() Type {
+	return ArrayType
 }
 
 func (ao *Array) Bool() bool {

internal/object/bool.go

@@ -12,8 +12,8 @@ func (b *Boolean) Bool() bool {
 	return b.Value
 }
 
-func (b *Boolean) Type() ObjectType {
-	return BOOLEAN_OBJ
+func (b *Boolean) Type() Type {
+	return BooleanType
 }
 
 func (b *Boolean) Inspect() string {

internal/object/builtin.go

@@ -11,8 +11,8 @@ func (b *Builtin) Bool() bool {
 	return true
 }
 
-func (b *Builtin) Type() ObjectType {
-	return BUILTIN_OBJ
+func (b *Builtin) Type() Type {
+	return BuiltinType
 }
 
 func (b *Builtin) Inspect() string {

internal/object/closure.go

@@ -15,8 +15,8 @@ func (cf *CompiledFunction) Bool() bool {
 	return true
 }
 
-func (cf *CompiledFunction) Type() ObjectType {
-	return COMPILED_FUNCTION_OBJ
+func (cf *CompiledFunction) Type() Type {
+	return CFunctionType
 }
 
 func (cf *CompiledFunction) Inspect() string {
@@ -36,8 +36,8 @@ func (c *Closure) Bool() bool {
 	return true
 }
 
-func (c *Closure) Type() ObjectType {
-	return CLOSURE_OBJ
+func (c *Closure) Type() Type {
+	return ClosureType
 }
 
 func (c *Closure) Inspect() string {

internal/object/error.go

@@ -8,8 +8,8 @@ func (e *Error) Bool() bool {
 	return false
 }
 
-func (e *Error) Type() ObjectType {
-	return ERROR_OBJ
+func (e *Error) Type() Type {
+	return ErrorType
 }
 
 func (e *Error) Inspect() string {

internal/object/function.go

@@ -16,8 +16,8 @@ func (f *Function) Bool() bool {
 	return false
 }
 
-func (f *Function) Type() ObjectType {
-	return FUNCTION_OBJ
+func (f *Function) Type() Type {
+	return FunctionType
 }
 
 func (f *Function) Inspect() string {
@@ -50,8 +50,8 @@ func (rv *ReturnValue) Bool() bool {
 	return true
 }
 
-func (rv *ReturnValue) Type() ObjectType {
-	return RETURN_VALUE_OBJ
+func (rv *ReturnValue) Type() Type {
+	return ReturnType
 }
 
 func (rv *ReturnValue) Inspect() string {

internal/object/hash.go

@@ -8,7 +8,7 @@ import (
 )
 
 type HashKey struct {
-	Type  ObjectType
+	Type  Type
 	Value uint64
 }
 
@@ -52,8 +52,8 @@ func (h *Hash) Bool() bool {
 	return len(h.Pairs) > 0
 }
 
-func (h *Hash) Type() ObjectType {
-	return HASH_OBJ
+func (h *Hash) Type() Type {
+	return HashType
 }
 
 func (h *Hash) Inspect() string {

internal/object/int.go

@@ -10,8 +10,8 @@ func (i *Integer) Bool() bool {
 	return i.Value != 0
 }
 
-func (i *Integer) Type() ObjectType {
-	return INTEGER_OBJ
+func (i *Integer) Type() Type {
+	return IntegerType
 }
 
 func (i *Integer) Inspect() string {

internal/object/module.go

@@ -12,8 +12,8 @@ func (m Module) String() string {
 	return m.Inspect()
 }
 
-func (m Module) Type() ObjectType {
-	return MODULE_OBJ
+func (m Module) Type() Type {
+	return ModuleType
 }
 
 func (m Module) Bool() bool {

internal/object/null.go

@@ -6,8 +6,8 @@ func (n *Null) Bool() bool {
 	return false
 }
 
-func (n *Null) Type() ObjectType {
-	return NULL_OBJ
+func (n *Null) Type() Type {
+	return NullType
 }
 
 func (n *Null) Inspect() string {

internal/object/object.go

@@ -3,24 +3,57 @@ package object
 import "fmt"
 
 // Type represents the type of an object
-type ObjectType string
+type Type int
 
 const (
-	INTEGER_OBJ           = "int"
-	BOOLEAN_OBJ           = "bool"
-	NULL_OBJ              = "null"
-	RETURN_VALUE_OBJ      = "return"
-	ERROR_OBJ             = "error"
-	FUNCTION_OBJ          = "fn"
-	STRING_OBJ            = "str"
-	BUILTIN_OBJ           = "builtin"
-	ARRAY_OBJ             = "array"
-	HASH_OBJ              = "hash"
-	COMPILED_FUNCTION_OBJ = "COMPILED_FUNCTION"
-	CLOSURE_OBJ           = "closure"
-	MODULE_OBJ            = "module"
+	NullType = iota
+	IntegerType
+	StringType
+	BooleanType
+	ReturnType
+	ErrorType
+	FunctionType
+	CFunctionType
+	BuiltinType
+	ClosureType
+	ArrayType
+	HashType
+	ModuleType
 )
 
+func (t Type) String() string {
+	switch t {
+	case NullType:
+		return "null"
+	case IntegerType:
+		return "int"
+	case StringType:
+		return "str"
+	case BooleanType:
+		return "bool"
+	case ReturnType:
+		return "Return"
+	case ErrorType:
+		return "error"
+	case FunctionType:
+		return "fn"
+	case CFunctionType:
+		return "CFunction"
+	case BuiltinType:
+		return "Builtin"
+	case ClosureType:
+		return "Closure"
+	case ArrayType:
+		return "array"
+	case HashType:
+		return "hash"
+	case ModuleType:
+		return "module"
+	default:
+		return "???"
+	}
+}
+
 // Comparable is the interface for comparing two Object and their underlying
 // values. It is the responsibility of the caller (left) to check for types.
 // Returns `true` iif the types and values are identical, `false` otherwise.
@@ -45,7 +78,7 @@ type Immutable interface {
 // `Type()` and `Inspect()` functions
 type Object interface {
 	fmt.Stringer
-	Type() ObjectType
+	Type() Type
 	Bool() bool
 	Inspect() string
 }

internal/object/str.go

@@ -17,8 +17,8 @@ func (s *String) Bool() bool {
 	return s.Value != ""
 }
 
-func (s *String) Type() ObjectType {
-	return STRING_OBJ
+func (s *String) Type() Type {
+	return StringType
 }
 
 func (s *String) Inspect() string {

internal/typing/typing.go

@@ -44,7 +44,7 @@ func RangeOfArgs(n, m int) CheckFunc {
 	}
 }
 
-func WithTypes(types ...object.ObjectType) CheckFunc {
+func WithTypes(types ...object.Type) CheckFunc {
 	return func(name string, args []object.Object) error {
 		for i, t := range types {
 			if i < len(args) && args[i].Type() != t {

internal/vm/vm.go

@@ -495,9 +495,9 @@ func (vm *VM) Run() error {
 
 func (vm *VM) executeSetItem(left, index, value object.Object) error {
 	switch {
-	case left.Type() == object.ARRAY_OBJ && index.Type() == object.INTEGER_OBJ:
+	case left.Type() == object.ArrayType && index.Type() == object.IntegerType:
 		return vm.executeArraySetItem(left, index, value)
-	case left.Type() == object.HASH_OBJ:
+	case left.Type() == object.HashType:
 		return vm.executeHashSetItem(left, index, value)
 	default:
 		return fmt.Errorf(
@@ -509,15 +509,15 @@ func (vm *VM) executeSetItem(left, index, value object.Object) error {
 
 func (vm *VM) executeGetItem(left, index object.Object) error {
 	switch {
-	case left.Type() == object.STRING_OBJ && index.Type() == object.INTEGER_OBJ:
+	case left.Type() == object.StringType && index.Type() == object.IntegerType:
 		return vm.executeStringGetItem(left, index)
-	case left.Type() == object.STRING_OBJ && index.Type() == object.STRING_OBJ:
+	case left.Type() == object.StringType && index.Type() == object.StringType:
 		return vm.executeStringIndex(left, index)
-	case left.Type() == object.ARRAY_OBJ && index.Type() == object.INTEGER_OBJ:
+	case left.Type() == object.ArrayType && index.Type() == object.IntegerType:
 		return vm.executeArrayGetItem(left, index)
-	case left.Type() == object.HASH_OBJ:
+	case left.Type() == object.HashType:
 		return vm.executeHashGetItem(left, index)
-	case left.Type() == object.MODULE_OBJ:
+	case left.Type() == object.ModuleType:
 		return vm.executeHashGetItem(left.(*object.Module).Attrs, index)
 	default:
 		return fmt.Errorf(
@@ -653,7 +653,7 @@ func (vm *VM) executeBinaryOperation(op code.Opcode) error {
 	switch {
 
 	// {"a": 1} + {"b": 2}
-	case op == code.OpAdd && left.Type() == object.HASH_OBJ && right.Type() == object.HASH_OBJ:
+	case op == code.OpAdd && left.Type() == object.HashType && right.Type() == object.HashType:
 		leftVal := left.(*object.Hash).Pairs
 		rightVal := right.(*object.Hash).Pairs
 		pairs := make(map[object.HashKey]object.HashPair)
@@ -666,7 +666,7 @@ func (vm *VM) executeBinaryOperation(op code.Opcode) error {
 		return vm.push(&object.Hash{Pairs: pairs})
 
 	// [1] + [2]
-	case op == code.OpAdd && left.Type() == object.ARRAY_OBJ && right.Type() == object.ARRAY_OBJ:
+	case op == code.OpAdd && left.Type() == object.ArrayType && right.Type() == object.ArrayType:
 		leftVal := left.(*object.Array).Elements
 		rightVal := right.(*object.Array).Elements
 		elements := make([]object.Object, len(leftVal)+len(rightVal))
@@ -674,7 +674,7 @@ func (vm *VM) executeBinaryOperation(op code.Opcode) error {
 		return vm.push(&object.Array{Elements: elements})
 
 	// [1] * 3
-	case op == code.OpMul && left.Type() == object.ARRAY_OBJ && right.Type() == object.INTEGER_OBJ:
+	case op == code.OpMul && left.Type() == object.ArrayType && right.Type() == object.IntegerType:
 		leftVal := left.(*object.Array).Elements
 		rightVal := int(right.(*object.Integer).Value)
 		elements := leftVal
@@ -683,7 +683,7 @@ func (vm *VM) executeBinaryOperation(op code.Opcode) error {
 		}
 		return vm.push(&object.Array{Elements: elements})
 	// 3 * [1]
-	case op == code.OpMul && left.Type() == object.INTEGER_OBJ && right.Type() == object.ARRAY_OBJ:
+	case op == code.OpMul && left.Type() == object.IntegerType && right.Type() == object.ArrayType:
 		leftVal := int(left.(*object.Integer).Value)
 		rightVal := right.(*object.Array).Elements
 		elements := rightVal
@@ -693,21 +693,21 @@ func (vm *VM) executeBinaryOperation(op code.Opcode) error {
 		return vm.push(&object.Array{Elements: elements})
 
 	// " " * 4
-	case op == code.OpMul && left.Type() == object.STRING_OBJ && right.Type() == object.INTEGER_OBJ:
+	case op == code.OpMul && left.Type() == object.StringType && right.Type() == object.IntegerType:
 		leftVal := left.(*object.String).Value
 		rightVal := right.(*object.Integer).Value
 		return vm.push(&object.String{Value: strings.Repeat(leftVal, int(rightVal))})
 	// 4 * " "
-	case op == code.OpMul && left.Type() == object.INTEGER_OBJ && right.Type() == object.STRING_OBJ:
+	case op == code.OpMul && left.Type() == object.IntegerType && right.Type() == object.StringType:
 		leftVal := left.(*object.Integer).Value
 		rightVal := right.(*object.String).Value
 		return vm.push(&object.String{Value: strings.Repeat(rightVal, int(leftVal))})
 
-	case leftType == object.BOOLEAN_OBJ && rightType == object.BOOLEAN_OBJ:
+	case leftType == object.BooleanType && rightType == object.BooleanType:
 		return vm.executeBinaryBooleanOperation(op, left, right)
-	case leftType == object.INTEGER_OBJ && rightType == object.INTEGER_OBJ:
+	case leftType == object.IntegerType && rightType == object.IntegerType:
 		return vm.executeBinaryIntegerOperation(op, left, right)
-	case leftType == object.STRING_OBJ && rightType == object.STRING_OBJ:
+	case leftType == object.StringType && rightType == object.StringType:
 		return vm.executeBinaryStringOperation(op, left, right)
 	default:
 		return fmt.Errorf("unsupported types for binary operation: %s %s", leftType, rightType)

repl.go

@@ -78,7 +78,7 @@ func VmREPL(args []string, debug bool) error {
 			continue
 		}
 
-		if val := mvm.LastPoppedStackElem(); val.Type() != object.NULL_OBJ {
+		if val := mvm.LastPoppedStackElem(); val.Type() != object.NullType {
 			fmt.Fprintln(t, val.Inspect())
 		}
 	}
@@ -176,7 +176,7 @@ func SimpleVmREPL(args []string, debug bool) {
 			continue
 		}
 
-		if val := mvm.LastPoppedStackElem(); val.Type() != object.NULL_OBJ {
+		if val := mvm.LastPoppedStackElem(); val.Type() != object.NullType {
 			fmt.Println(val.Inspect())
 		}
 	}