Simplified Equality

builtins/find.go

@@ -1,6 +1,9 @@
 package builtins
 
-import "monkey/object"
+import (
+	"monkey/object"
+	"sort"
+)
 
 import (
 	"strings"
@@ -21,15 +24,14 @@ func Find(args ...object.Object) object.Object {
 			return newError("expected arg #2 to be `str` got got=%T", args[1])
 		}
 	} else if haystack, ok := args[0].(*object.Array); ok {
-		needle := args[1]
-		index := -1
-		for i, el := range haystack.Elements {
-			if cmp, ok := el.(object.Comparable); ok && cmp.Equal(needle) {
-				index = i
-				break
-			}
+		needle := args[1].(object.Comparable)
+		i := sort.Search(len(haystack.Elements), func(i int) bool {
+			return needle.Compare(haystack.Elements[i]) == 0
+		})
+		if i < len(haystack.Elements) && needle.Compare(haystack.Elements[i]) == 0 {
+			return &object.Integer{Value: int64(i)}
 		}
-		return &object.Integer{Value: int64(index)}
+		return &object.Integer{Value: -1}
 	} else {
 		return newError("expected arg #1 to be `str` or `array` got got=%T", args[0])
 	}

evaluator/evaluator.go

@@ -337,6 +337,7 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 			elements = append(elements, leftVal...)
 		}
 		return &object.Array{Elements: elements}
+
 	// 3 * [1]
 	case operator == "*" && left.Type() == object.INTEGER_OBJ && right.Type() == object.ARRAY_OBJ:
 		leftVal := int(left.(*object.Integer).Value)
@@ -352,24 +353,33 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 		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:
 		leftVal := left.(*object.Integer).Value
 		rightVal := right.(*object.String).Value
 		return &object.String{Value: strings.Repeat(rightVal, int(leftVal))}
 
+	case operator == "==":
+		return nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) == 0)
+	case operator == "!=":
+		return nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) != 0)
+	case operator == "<=":
+		return nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) < 1)
+	case operator == ">=":
+		return nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) > -1)
+	case operator == "<":
+		return nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) == -1)
+	case operator == ">":
+		return nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) == 1)
+
 	case left.Type() == object.BOOLEAN_OBJ && right.Type() == object.BOOLEAN_OBJ:
 		return evalBooleanInfixExpression(operator, left, right)
 	case left.Type() == object.INTEGER_OBJ && right.Type() == object.INTEGER_OBJ:
 		return evalIntegerInfixExpression(operator, left, right)
 	case left.Type() == object.STRING_OBJ && right.Type() == object.STRING_OBJ:
 		return evalStringInfixExpression(operator, left, right)
-	case operator == "==":
-		return nativeBoolToBooleanObject(left == right)
-	case operator == "!=":
-		return nativeBoolToBooleanObject(left != right)
-	case left.Type() != right.Type():
-		return newError("type mismatch: %s %s %s", left.Type(), operator, right.Type())
+
 	default:
 		return newError("unknown operator: %s %s %s", left.Type(), operator, right.Type())
 	}
@@ -380,10 +390,6 @@ func evalBooleanInfixExpression(operator string, left, right object.Object) obje
 	rightVal := right.(*object.Boolean).Value
 
 	switch operator {
-	case "==":
-		return nativeBoolToBooleanObject(left == right)
-	case "!=":
-		return nativeBoolToBooleanObject(leftVal != rightVal)
 	case "&&":
 		return &object.Boolean{Value: leftVal && rightVal}
 	case "||":
@@ -400,14 +406,6 @@ func evalStringInfixExpression(operator string, left object.Object, right object
 	switch operator {
 	case "+":
 		return &object.String{Value: leftVal + rightVal}
-	case "<":
-		return nativeBoolToBooleanObject(leftVal < rightVal)
-	case ">":
-		return nativeBoolToBooleanObject(leftVal > rightVal)
-	case "==":
-		return nativeBoolToBooleanObject(leftVal == rightVal)
-	case "!=":
-		return nativeBoolToBooleanObject(leftVal != rightVal)
 	default:
 		return newError("unknown operator: %s %s %s", left.Type(), operator, right.Type())
 	}

evaluator/evaluator_test.go

@@ -118,6 +118,7 @@ func TestIfElseExpression(t *testing.T) {
 	}
 
 	for _, tt := range tests {
+		t.Log(tt.input)
 		evaluated := testEval(tt.input)
 		integer, ok := tt.expected.(int)
 		if ok {
@@ -184,11 +185,11 @@ func TestErrorHandling(t *testing.T) {
 	}{
 		{
 			"5 + true;",
-			"type mismatch: int + bool",
+			"unknown operator: int + bool",
 		},
 		{
 			"5 + true; 5;",
-			"type mismatch: int + bool",
+			"unknown operator: int + bool",
 		},
 		{
 			"-true",

object/array.go

@@ -13,6 +13,7 @@ type Array struct {
 func (ao *Array) Type() ObjectType {
 	return ARRAY_OBJ
 }
+
 func (ao *Array) Inspect() string {
 	var out bytes.Buffer
 
@@ -30,25 +31,34 @@ func (ao *Array) Inspect() string {
 func (ao *Array) String() string {
 	return ao.Inspect()
 }
-func (ao *Array) Equal(other Object) bool {
+
+func (a *Array) Less(i, j int) bool {
+	if cmp, ok := a.Elements[i].(Comparable); ok {
+		return cmp.Compare(a.Elements[j]) == -1
+	}
+	return false
+}
+
+func (ao *Array) Compare(other Object) int {
 	if obj, ok := other.(*Array); ok {
 		if len(ao.Elements) != len(obj.Elements) {
-			return false
+			return -1
 		}
 		for i, el := range ao.Elements {
 			cmp, ok := el.(Comparable)
 			if !ok {
-				return false
+				return -1
 			}
-			if !cmp.Equal(obj.Elements[i]) {
-				return false
+			if cmp.Compare(obj.Elements[i]) != 0 {
+				return cmp.Compare(obj.Elements[i])
 			}
 		}
 
-		return true
+		return 0
 	}
-	return false
+	return -1
 }
+
 func (ao *Array) Copy() *Array {
 	elements := make([]Object, len(ao.Elements))
 	for i, e := range ao.Elements {
@@ -70,10 +80,3 @@ func (ao *Array) Len() int {
 func (ao *Array) Swap(i, j int) {
 	ao.Elements[i], ao.Elements[j] = ao.Elements[j], ao.Elements[i]
 }
-
-func (ao *Array) Less(i, j int) bool {
-	if cmp, ok := ao.Elements[i].(Comparable); ok {
-		return cmp.Less(ao.Elements[j])
-	}
-	return false
-}

object/bool.go

@@ -11,31 +11,29 @@ type Boolean struct {
 func (b *Boolean) Type() ObjectType {
 	return BOOLEAN_OBJ
 }
+
 func (b *Boolean) Inspect() string {
 	return fmt.Sprintf("%t", b.Value)
 }
+
 func (b *Boolean) Clone() Object {
 	return &Boolean{Value: b.Value}
 }
+
 func (b *Boolean) String() string {
 	return b.Inspect()
 }
-func (b *Boolean) Equal(other Object) bool {
-	if obj, ok := other.(*Boolean); ok {
-		return b.Value == obj.Value
-	}
-	return false
-}
-func (b *Boolean) Int() int64 {
+
+func (b *Boolean) Int() int {
 	if b.Value {
 		return 1
 	}
 	return 0
 }
 
-func (b *Boolean) Less(other Object) bool {
+func (b *Boolean) Compare(other Object) int {
 	if obj, ok := other.(*Boolean); ok {
-		return b.Int() < obj.Int()
+		return b.Int() - obj.Int()
 	}
-	return false
+	return 1
 }

object/hash.go

@@ -47,6 +47,7 @@ type Hash struct {
 func (h *Hash) Type() ObjectType {
 	return HASH_OBJ
 }
+
 func (h *Hash) Inspect() string {
 	var out bytes.Buffer
 
@@ -64,28 +65,29 @@ func (h *Hash) Inspect() string {
 func (h *Hash) String() string {
 	return h.Inspect()
 }
-func (h *Hash) Equal(other Object) bool {
+
+func (h *Hash) Compare(other Object) int {
 	if obj, ok := other.(*Hash); ok {
 		if len(h.Pairs) != len(obj.Pairs) {
-			return false
+			return -1
 		}
 		for _, pair := range h.Pairs {
 			left := pair.Value
 			hashed := left.(Hashable)
 			right, ok := obj.Pairs[hashed.HashKey()]
 			if !ok {
-				return false
+				return -1
 			}
 			cmp, ok := left.(Comparable)
 			if !ok {
-				return false
+				return -1
 			}
-			if !cmp.Equal(right.Value) {
-				return false
+			if cmp.Compare(right.Value) != 0 {
+				return cmp.Compare(right.Value)
 			}
 		}
 
-		return true
+		return 0
 	}
-	return false
+	return -1
 }

object/int.go

@@ -9,24 +9,29 @@ type Integer struct {
 func (i *Integer) Type() ObjectType {
 	return INTEGER_OBJ
 }
+
 func (i *Integer) Inspect() string {
 	return fmt.Sprintf("%d", i.Value)
 }
+
 func (i *Integer) Clone() Object {
 	return &Integer{Value: i.Value}
 }
+
 func (i *Integer) String() string {
 	return i.Inspect()
 }
-func (i *Integer) Equal(other Object) bool {
+
+func (i *Integer) Compare(other Object) int {
 	if obj, ok := other.(*Integer); ok {
-		return i.Value == obj.Value
+		switch {
+		case i.Value < obj.Value:
+			return -1
+		case i.Value > obj.Value:
+			return 1
+		default:
+			return 0
+		}
 	}
-	return false
-}
-func (i *Integer) Less(other Object) bool {
-	if obj, ok := other.(*Integer); ok {
-		return i.Value < obj.Value
-	}
-	return true
+	return -1
 }

object/null.go

@@ -5,16 +5,18 @@ type Null struct{}
 func (n *Null) Type() ObjectType {
 	return NULL_OBJ
 }
+
 func (n *Null) Inspect() string {
 	return "null"
 }
+
 func (n *Null) String() string {
 	return n.Inspect()
 }
-func (n *Null) Equal(other Object) bool {
-	_, ok := other.(*Null)
-	return ok
-}
-func (n *Null) Less(other Object) bool {
-	return false
+
+func (n *Null) Compare(other Object) int {
+	if _, ok := other.(*Null); ok {
+		return 0
+	}
+	return 1
 }

object/object.go

@@ -22,8 +22,7 @@ const (
 // values. It is the responsibility of the caller (left) to check for types.
 // Returns `true` iif the types and values are identical, `false` otherwise.
 type Comparable interface {
-	Equal(other Object) bool
-	Less(other Object) bool
+	Compare(other Object) int
 }
 
 // Immutable is the interface for all immutable objects which must implement

object/str.go

@@ -9,24 +9,29 @@ type String struct {
 func (s *String) Type() ObjectType {
 	return STRING_OBJ
 }
+
 func (s *String) Inspect() string {
 	return fmt.Sprintf("%#v", s.Value)
 }
+
 func (s *String) Clone() Object {
 	return &String{Value: s.Value}
 }
+
 func (s *String) String() string {
 	return s.Value
 }
-func (s *String) Equal(other Object) bool {
+
+func (s *String) Compare(other Object) int {
 	if obj, ok := other.(*String); ok {
-		return s.Value == obj.Value
+		switch {
+		case s.Value < obj.Value:
+			return -1
+		case s.Value > obj.Value:
+			return 1
+		default:
+			return 0
+		}
 	}
-	return false
-}
-func (s *String) Less(other Object) bool {
-	if obj, ok := other.(*String); ok {
-		return s.Value < obj.Value
-	}
-	return false
+	return 1
 }

vm/vm.go

@@ -659,39 +659,18 @@ func (vm *VM) executeComparison(op code.Opcode) error {
 	right := vm.pop()
 	left := vm.pop()
 
-	if left.Type() == object.INTEGER_OBJ && right.Type() == object.INTEGER_OBJ {
-		return vm.executeIntegerComparison(op, left, right)
-	}
-
-	if left.Type() == object.STRING_OBJ && right.Type() == object.STRING_OBJ {
-		return vm.executeStringComparison(op, left, right)
-	}
-
 	switch op {
 	case code.OpEqual:
-		return vm.push(nativeBoolToBooleanObject(right == left))
+		return vm.push(nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) == 0))
 	case code.OpNotEqual:
-		return vm.push(nativeBoolToBooleanObject(right != left))
-	default:
-		return fmt.Errorf("unknown operator: %d (%s %s)", op, left.Type(), right.Type())
-	}
-}
-
-func (vm *VM) executeIntegerComparison(op code.Opcode, left, right object.Object) error {
-	leftValue := left.(*object.Integer).Value
-	rightValue := right.(*object.Integer).Value
-
-	switch op {
-	case code.OpEqual:
-		return vm.push(nativeBoolToBooleanObject(rightValue == leftValue))
-	case code.OpNotEqual:
-		return vm.push(nativeBoolToBooleanObject(rightValue != leftValue))
-	case code.OpGreaterThan:
-		return vm.push(nativeBoolToBooleanObject(leftValue > rightValue))
+		return vm.push(nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) != 0))
 	case code.OpGreaterThanEqual:
-		return vm.push(nativeBoolToBooleanObject(leftValue >= rightValue))
+		return vm.push(nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) > -1))
+	case code.OpGreaterThan:
+		return vm.push(nativeBoolToBooleanObject(left.(object.Comparable).Compare(right) == 1))
 	default:
-		return fmt.Errorf("unknown operator: %d", op)
+		return fmt.Errorf("unknown operator: %d (%s %s)",
+			op, left.Type(), right.Type())
 	}
 }
 
@@ -826,24 +805,6 @@ func (vm *VM) executeStringIndex(str, index object.Object) error {
 	)
 }
 
-func (vm *VM) executeStringComparison(op code.Opcode, left, right object.Object) error {
-	leftValue := left.(*object.String).Value
-	rightValue := right.(*object.String).Value
-
-	switch op {
-	case code.OpEqual:
-		return vm.push(nativeBoolToBooleanObject(rightValue == leftValue))
-	case code.OpNotEqual:
-		return vm.push(nativeBoolToBooleanObject(rightValue != leftValue))
-	case code.OpGreaterThan:
-		return vm.push(nativeBoolToBooleanObject(leftValue > rightValue))
-	case code.OpGreaterThanEqual:
-		return vm.push(nativeBoolToBooleanObject(leftValue >= rightValue))
-	default:
-		return fmt.Errorf("unknown operator: %d", op)
-	}
-}
-
 func nativeBoolToBooleanObject(input bool) *object.Boolean {
 	if input {
 		return True