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Spec: modules

File model​

A module today is one source file. The file consists of zero or more top-level function declarations:

File = { FnDecl }

There are no imports today. There is no notion of a package or a multi-file unit.

Entry point​

The entry point is a function named main with no parameters and a return type of i32. The implementation is required to invoke main at program start and use its return value as the process exit code.

Visibility​

All top-level declarations in a file are visible to every other top-level declaration in the same file. There is no pub / private distinction today.

Multi-file projects (planned)​

The plan is:

  • A module will be a single file, declared with a top-of-file module name.
  • A package will be a directory of modules, with module-level import statements.
  • Visibility will be controlled with pub.

The full design is (planned); see planned: roadmap.

Constants (planned)​

Top-level const declarations of kind nat will be usable in shape positions. Today, shapes must be either literals, shape parameters, or simple shape arithmetic; module-level constants of nat-kind are not yet supported.

Attributes​

The function-attribute syntax @<ident> shipped in v0.13. The only attribute the type checker enforces today is @io, the I/O effect (see Functions: purity and effects and Effects (@io)). Other attributes (@inline, @noinline, @kernel, …) are reserved by the grammar but currently ignored by later passes — they are (planned).