package evaluator import ( "fmt" "monkey/object" ) var builtins = map[string]*object.Builtin{ "len": { Fn: func(args ...object.Object) object.Object { if len(args) != 1 { return newError("wrong number of arguments. got=%d, want=1", len(args)) } switch arg := args[0].(type) { case *object.Array: return &object.Integer{Value: int64(len(arg.Elements))} case *object.String: return &object.Integer{Value: int64(len(arg.Value))} default: return newError("argument to `len` not supported, got %s", args[0].Type()) } }, }, "puts": { Fn: func(args ...object.Object) object.Object { for _, arg := range args { fmt.Println(arg.Inspect()) } return NULL }, }, "first": { Fn: func(args ...object.Object) object.Object { if len(args) != 1 { return newError("wrong number of arguments. got=%d, want=1", len(args)) } if args[0].Type() != object.ARRAY { return newError("argument to `first` must be ARRAY, got %s", args[0].Type()) } arr := args[0].(*object.Array) if len(arr.Elements) > 0 { return arr.Elements[0] } return NULL }, }, "last": { Fn: func(args ...object.Object) object.Object { if len(args) != 1 { return newError("wrong number of arguments. got=%d, want=1", len(args)) } if args[0].Type() != object.ARRAY { return newError("argument to `last` must be ARRAY, got %s", args[0].Type()) } arr := args[0].(*object.Array) length := len(arr.Elements) if length > 0 { return arr.Elements[length-1] } return NULL }, }, "rest": { Fn: func(args ...object.Object) object.Object { if len(args) != 1 { return newError("wrong number of arguments. got=%d, want=1", len(args)) } if args[0].Type() != object.ARRAY { return newError("argument to `rest` must be ARRAY, got %s", args[0].Type()) } arr := args[0].(*object.Array) length := len(arr.Elements) if length > 0 { newElements := make([]object.Object, length-1) copy(newElements, arr.Elements[1:length]) return &object.Array{Elements: newElements} } return NULL }, }, "push": { Fn: func(args ...object.Object) object.Object { if len(args) != 2 { return newError("wrong number of arguments. got=%d, want=2", len(args)) } if args[0].Type() != object.ARRAY { return newError("argument to `push` must be ARRAY, got %s", args[0].Type()) } arr := args[0].(*object.Array) length := len(arr.Elements) newElements := make([]object.Object, length+1) copy(newElements, arr.Elements) newElements[length] = args[1] return &object.Array{Elements: newElements} }, }, }