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weekly 2023-12-11

Β· 2 min read

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.

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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)) (array.new $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 {
  receiver
    .method1()
    .method2()
    .method3()
}

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
  }
  function(
    arg1,
    arg2 // before: must add comma here
  )
}

4. String interpolation now supports unicode​

let s = "string interpolate unicode \( δΈ­ζ–‡ )"

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.