hetu_script 0.1.2
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Hetu is a lightweight script language for embedding in Flutter apps.

Hetu Script #

Warning #

Hetu is early WIP! We are focusing on making Hetu stable and feature complete right now.

Discussion group:

Discord: https://discord.gg/Q8JWQYEw

QQ 群: 812529118

Introduction #

Hetu is a lightweight script language purely written in Dart for embedding in Flutter apps. The main goal is to enable Flutter app have hotfix and scripting ability.

We did not choose to use another existing language to achieve the goal. Because we want to keep the language simple, and keep it away from interference of other language's complex implementation and their irrelative-to-Flutter eco-system, and make the debug process pain-free and remain in Dart realms.

It takes very little time to bind almost anything in Dart/Flutter into Hetu and use similar grammar to write your app. And to communicate with classes & functions in Dart is very easy.

Quick start #

Hetu's grammar is close to typescript/kotlin/swift and other modern languages, need very little time to get familar with.

  • Optional semicolon.
  • Function is declared with 'fun, get, set, construct'.
  • Optional type annotation. Variable declared with 'let, const' will infer its type from its initializer expression.

Syntax referrence

In your Dart code, you can interpret a script file:

import 'package:hetu_script/hetu_script.dart';

void main() async {
  var hetu = Hetu();
  await hetu.init();
  await hetu.import('hello.ht', invokeFunc: 'main');

While [hello.ht] is the script file written in Hetu, here is an example:

// Define a class.
class Person {
  var name: str
  construct (name: str) {
    this.name = name
  fun greeting {
    print('Hi! I\'m', name)

// This is where the script starts executing.
fun main {
  var ht = Person('Hetu')

Binding #

Hetu script is purely written in Dart, so passing object to and from script is extremely easy.

Check this page for more information about how to bind external classes, functions, enums and how to passing object and functions between Dart and script.

import 'package:hetu_script/hetu_script.dart';

void main() async {
  var hetu = Hetu();
  await hetu.init(externalFunctions: {
    'hello': () => {'greeting': 'hello'},
  await hetu.eval(r'''
      external fun hello
      fun main {
        var dartValue = hello()
        print('dart value:', dartValue)
        dartValue['foo'] = 'bar'
        return dartValue

  var hetuValue = hetu.invoke('main');

  print('hetu value: $hetuValue');

Command line tool #

Hetu has a command line REPL tool for testing. You can activate by the following command:

dart pub global activate hetu_script

Then you can use command line tool 'hetu' in any directory on your computer. (If you are facing any problems, please check this official document about pub global activate)

Currently there are two command: [run] for evaluate a script file and [fmt] for format the scrip file.

More information can be found by enter [hetu -h].

If no command and option is provided, enter REPL mode.

In REPL mode, every exrepssion you entered will be evaluated and print out immediately.

If you want to write multiple line in REPL mode, use '\' to end a line.

>>>var a = 42
>>>fun hello {\
return a }
function hello() -> any // repl print
42 // repl print

Referrences: #

Apps that embedded Hetu: #

Monster Hunter Otomo: RiserockingdiceA unofficial game companion app for Capcom's Monster Hunter: RiseiOSClosed Source
pub points



Hetu is a lightweight script language for embedding in Flutter apps.

Repository (GitHub)
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API reference




analyzer, args, characters, meta, path, pub_semver, quiver


Packages that depend on hetu_script