This Month in Mun - October 2020

October 31, 2020, The Mun Team

When Mun takes part in Hacktoberfest, there’s one thing you can be sure of; lots and lots of pull requests. This month saw us finalise some big new features and refactors that inch us ever closer to a Mun v0.3 release.


This month Mun partook in the DigitalOcean Hacktoberfest - a great event aimed at supporting the open source community. Our goal was to get as many members to contribute at least 4 pull requests, such that they could win either a limited edition T-shirt or plant a tree. That led to the following contributions

  • feat: add mdbook plugin for testing mun code in book [PR#263] This allows testing of Mun code in mdbook, guaranteeing that the Mun book remains up-to-date when we update our Mun compiler and runtime.
  • docs: fix broken book link and CoC link [PR#284]

We are very thankful for your contributions and we hope to see more of them in the future!

If you are also interested in helping develop Mun - but are not sure where to start - feel free to take a look at our good first issues or reach out to us on Discord or Twitter. To support our cause, please consider donating to our Open Collective or Github Sponsors.

Mun v0.3 progress

This month we finally landed the long-awaited compiler and language-server support for multiple files in a single project:

  • feature: adds modules and visibility [PR#283]
      // mod.mun
      struct Foo;
      fn main() -> self::Foo {
      fn bar() -> Foo {
          super::Foo  // undefined value
      fn baz() -> Foo {
      // foo.mun
      struct Foo;
      fn bar() -> Foo {
          super::Foo  // mismatched type
      fn baz() -> package::Foo {
      fn nested() -> self::Foo {
    Those familiar with Rust conventions will notice that Mun:
    • uses mod.mun instead of lib.mun for the top-level file; and
    • does not require you to add a mod foo; statement to the mod.mun file. Instead all files in the src folder are assumed part of the file tree.
  • feature: adds super self and package keywords [PR#8]

In addition, we laid most of the groundwork for runtime linking of multiple Mun libraries:

  • fix(codegen): alignment of struct fields [PR#285]
  • feat(codegen): add AsValue macro support for enums [PR#286]
    pub enum TypeInfoData<'ink> {

Together with soon to be merged PRs, that should bring us within earshot of the Mun v0.3 release:

  • refactor: make type-specific data (such as StructInfo) part of TypeInfo [PR#287] [PR#10] [PR#9]
  • WIP: refactor: replace TypeInfo with TypeRef for runtime linking of types [PR#268]

For more details, please check out our high-level roadmap on Github that details new features for the upcoming three releases - Mun v0.3, v0.4, and v0.5 - as well as a backlog of features that are still to come.

Finally, we also performed some fixes and bumped the supported Rust version: