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weekly 2024-05-27

· 2 min read

MoonBit is a Rust-like programming language (with GC support) and toolchain optimized for WebAssembly.

Language Update​

  • Breaking Change: Restructure APIs of MoonBit Core library.
    • Placing all immutable data structures under the immut path, for example, from @immutable_hashmap.Map to @immut/hashmap.Map.
// Before
let a : @immutable_hashmap.Map[Int, Int] = @immutable_hashmap.make()
// After
let a : @immut/hashmap.Map[Int, Int] = @immut/hashmap.make()
  • Performance optimization for the Option[T] type in the core library:
    • When the type T is a reference type, for values of type Option[T], Some(v) will be directly compiled into v, and None will be compiled into ref.null in the wasm-gc backend, or undefined in the JavaScript backend, thus avoiding memory allocation.
  • Introduced fn panicT -> T function in the core library, which can be used within test blocks where the test name must start with "panic":
test "panic test ok" {
  panic() // Test passes
}

test "panic test failed" {
  () // Test fails
}

IDE Update​

  • VS Code extension: Added test and for code snippets. test snippet: test.gif for snippet: for.gif

Build System Update​

  • Initialization: moon new now automatically initializes version control for new projects, currently supporting git
  • Testing: You can now specify multiple packages to test
moon test -p a b c
moon test -p a -p b -p c

Toolchain Update​

  • Installation: You can now specify a version number for installation
# Mac and Linux Users
# Download the latest version
curl -fsSL https://cli.moonbitlang.com/install/unix.sh | bash
# Download the bleeding edge version
curl -fsSL https://cli.moonbitlang.com/install/unix.sh | bash -s bleeding
# Download a specific version
curl -fsSL https://cli.moonbitlang.com/install/unix.sh | bash -s 0.1.20240520+b1f30d5e1
# Windows Users
# Download the latest version
irm cli.moonbitlang.cn/install/powershell.ps1 | iex
# Download a specific version
$env:MOONBIT_INSTALL_VERSION = "0.1.20240520+b1f30d5e1"; irm cli.moonbitlang.cn/install/powershell.ps1 | iex