The MoonBit Update——1211

In December 2023, MoonBit underwent Alpha testing. This post aims to introduce recent updates to MoonBit’s language and toolchain, along with applications developed using MoonBit.

Changes in MoonBit Language

Here’s the translation of the release notes into English:

1. Support for defining newtype using the type keyword:

type MyInt Int derive(Show)

fn init {
  let x = MyInt::MyInt(5)
  println(x) // Output: MyInt(5)
  println(x.0) // Output: 5

2. Support for inline Wasm functions, for example:

fn char_to_string(c: Char) -> String =
   "(func $char_to_string (param $c i32) (result (ref $moonbit.string)) ( $moonbit.string (local.get $c) (i32.const 1)))"

For now, inline Wasm functions are only supported for the wasm-gc backend.

3. Improved automatic semicolon insertion.

Chained method call in the following style is now supported:

fn init {

and there is no need for trailing comma in multi-line application and record creation anymore:

fn init {
  let record = {
    x: 1,
    y: "abc" // before: must add comma here
    arg2 // before: must add comma here

4. String interpolation now supports Unicode

let s = "string interpolate unicode \( 中文 )"

5. Optimized string highlighting.

  • Before:

  • After:

6. Built-in type improvements:

  • String:

    • Added String::make:
fn init {
  let s = String::make(3, 'a')
  println(s) // Output: aaa
  • Fixed String::compare. Before, String::compare only compared lengths; now, it compares in dictionary order.

  • Bytes and Buffer:

    • Added Bytes-related functions: blit, to_string, of_string, sub_string, blit_from_string, copy, set_utf8_char.

    • Introduced Buffer type and related functions: to_string, make, write_string, write_char, length.

  • Option now includes default implementations for Eq/Compare/Show/Default, and Ref/Array includes a default implementation for Show.