Modules

Ranty modules are .ranty files whose top-level result becomes the imported module value. In typical use a module returns a map of functions and values.

For compatibility with Rant 4, legacy .rant modules are also supported.

Writing modules

A module is just a program that returns a value, usually a map:

# seq.ranty

<%module = (::)>

[$module/fib: n] {
  (:) [rep: <n>] { @edit f: <f> (<f/-2 ? 0> + <f/-1 ? 1>) }
}

<module>

Importing modules

Use @require to load a module and bind it by filename:

@require "test-module"

The default resolver prefers .ranty when no extension is supplied, falls back to .rant, preserves explicit .ranty and .rant paths, and normalizes relative paths before loading.

Embedding hosts are not limited to this behavior. They can replace the default filesystem resolver entirely; see Module Resolvers.

Search order

When you use @require, the default resolver checks the following locations in order:

1. the importing program's directory, if the caller came from a file-backed program,
2. the resolver's local modules path, or the host working directory when no local path is configured,
3. the global modules path from RANTY_MODULES_PATH when global modules are enabled.

Caching

Modules are cached per Ranty context. Requiring the same module again returns the cached value instead of recompiling or re-running the module body.

Relative paths

Relative paths are resolved relative to the active search roots:

@require tm: "test-module"

Failures

• Missing modules raise MODULE_ERROR.
• Compile failures in module source raise MODULE_ERROR with compiler diagnostics attached to the runtime error description.
• Runtime failures during module initialization propagate as ordinary runtime errors from the module body.
• Cyclic imports are rejected deterministically as MODULE_ERROR.

Host customization

The behavior described above is specific to the built-in DefaultModuleResolver.

Embedding hosts can instead:

• serve modules from memory or another backing store,
• restrict which module paths are legal,
• disable modules entirely with NoModuleResolver.

See Module Resolvers for the resolver contract, DefaultModuleResolver configuration, and host-side preloading with try_load_global_module().