added array return for len with multiple arguments

Author: Aditya-Chowdhary

MyCode/evaluator/evaluator_test.go

@@ -332,13 +332,14 @@ func TestBuiltinFunctions(t *testing.T) {
 		input    string
 		expected interface{}
 	}{
+		{`len()`, "at least one argument required. got=0"},
 		{`len("")`, 0},
 		{`len("four")`, 4},
 		{`len("hello world")`, 11},
-		{`len(1)`, "argument to `len` not supported, got INTEGER"},
-		{`len("one", "two")`, "wrong number of arguments. got=2, want=1"},
-		{`len(1)`, "argument to `len` not supported, got INTEGER"},
-		{`len("one", "two")`, "wrong number of arguments. got=2, want=1"},
+		{`len(1)`, "argument to `len` not supported, got INTEGER, position 0"},
+		{`len("one", "two")`, []int{3, 3}},
+		{`len("one", [1, 2])`, []int{3, 2}},
+		{`len("one", [1, 2], 5)`, "argument to `len` not supported, got INTEGER, position 2"},
 		{`len([1, 2, 3])`, 3},
 		{`len([])`, 0},
 		{`puts("hello", "world!")`, nil},
@@ -486,8 +487,8 @@ func TestHashLiterals(t *testing.T) {
 		(&object.String{Value: "two"}).HashKey():   2,
 		(&object.String{Value: "three"}).HashKey(): 3,
 		(&object.Integer{Value: 4}).HashKey():      4,
-		TRUE.HashKey():   5,
-		FALSE.HashKey():  6,
+		TRUE.HashKey():                             5,
+		FALSE.HashKey():                            6,
 	}
 
 	if len(result.Pairs) != len(expected) {
@@ -574,7 +575,6 @@ func testIntegerObject(t *testing.T, obj object.Object, expected int64) bool {
 	return true
 }
 
-
 func testBooleanObject(t *testing.T, obj object.Object, expected bool) bool {
 	result, ok := obj.(*object.Boolean)
 	if !ok {
@@ -597,4 +597,4 @@ func testNullObject(t *testing.T, obj object.Object) bool {
 	}
 
 	return true
-}
+}

MyCode/object/builtins.go

@@ -7,21 +7,30 @@ var Builtins = []struct {
 	Builtin *Builtin
 }{
 	{
-		// TODO if passed multiple arguments, return length of all values?
 		"len",
 		&Builtin{
 			Fn: func(args ...Object) Object {
-				if len(args) != 1 {
-					return newError("wrong number of arguments. got=%d, want=1", len(args))
+				if len(args) < 1 {
+					return newError("at least one argument required. got=%d", len(args))
+				}
+
+				lengths := make([]Object, len(args))
+				for i, v := range args {
+
+					switch arg := v.(type) {
+					case *Array:
+						lengths[i] = &Integer{Value: int64(len(arg.Elements))}
+					case *String:
+						lengths[i] = &Integer{Value: int64(len(arg.Value))}
+					default:
+						return newError("argument to `len` not supported, got %s, position %d", v.Type(), i)
+					}
 				}
 
-				switch arg := args[0].(type) {
-				case *Array:
-					return &Integer{Value: int64(len(arg.Elements))}
-				case *String:
-					return &Integer{Value: int64(len(arg.Value))}
-				default:
-					return newError("argument to `len` not supported, got %s", args[0].Type())
+				if len(lengths) == 1 {
+					return lengths[0]
+				} else {
+					return &Array{Elements: lengths}
 				}
 			},
 		},

MyCode/test.mky

@@ -28,6 +28,10 @@ let fibonacci = fn(x) {
     }
 };
 
+let arg = ["one", "hello", [1, 2, 3]]
+puts(len(arg))
+puts(len(arg, "byebye", "hi"))
+
 let map = fn(arr, f) {
     let iter = fn(arr, accumulated) {
         if (len(arr) == 0) {

MyCode/vm/vm_test.go

@@ -416,22 +416,24 @@ func TestCallingFunctionsWithWrongArguments(t *testing.T) {
 
 func TestBuiltinFunctions(t *testing.T) {
 	tests := []vmTestCase{
+		{`len()`, &object.Error{
+			Message: "at least one argument required. got=0",
+		}},
 		{`len("")`, 0},
 		{`len("four")`, 4},
 		{`len("hello world")`, 11},
 		{
 			`len(1)`,
 			&object.Error{
-				Message: "argument to `len` not supported, got INTEGER",
-			},
-		},
-		{`len("one", "two")`,
-			&object.Error{
-				Message: "wrong number of arguments. got=2, want=1",
+				Message: "argument to `len` not supported, got INTEGER, position 0",
 			},
 		},
+		{`len("one", "two")`, []int{3, 3}},
 		{`len([1, 2, 3])`, 3},
 		{`len([])`, 0},
+		{`len("one", [1, 2], 5)`, &object.Error {
+			Message:  "argument to `len` not supported, got INTEGER, position 2",
+		}},
 		{`puts("hello", "world!")`, Null},
 		{`first([1, 2, 3])`, 1},
 		{`first([])`, Null},