package object // First ... func First(args ...Object) Object { if len(args) != 1 { return newError("wrong number of arguments. got=%d, want=1", len(args)) } if args[0].Type() != ARRAY_OBJ { return newError("argument to `first` must be ARRAY, got %s", args[0].Type()) } arr := args[0].(*Array) if len(arr.Elements) > 0 { return arr.Elements[0] } return nil }