Modules

This page describes namespaces, imports, and file-level modules in Lutra.

Qualified names¶

Lutra uses :: to separate module path segments.

std::cmp
std::option::or_default
project::pg::from_albums

Import definitions¶

Use import to bring a name or module into scope.

import std::cmp

Aliased imports¶

You can rename an import with as.

import chinook as c

Then use the alias as the module name:

c::Genre
c::get_albums_by_genre

Grouped imports¶

You can import several names from the same module path.

import std::(Date, math::pow)
import std::(flat_map, filter, apply_until_empty)

Module definitions¶

Use module to define a nested module inline.

module chinook {
  func get_albums(): [Album] -> []

  func get_album_by_id(album_id: int64): Album? -> (
    get_albums()
    | std::find(this -> this.id == album_id)
  )
}

Definitions inside a module are referenced through the module path.

chinook::get_album_by_id(3)

File modules and submodule¶

Lutra builds a module tree from files and directories.

When a directory contains module.lt, Lutra also loads:

• files in the same directory that begin with submodule, and
• nested directories that contain their own module.lt, recursively.

This lets multiple files contribute definitions to the same module path.

submodule

func hello(a: float64, b: uint64): int64 -> 1

Note that compiler will always load the whole project structure, even when provided with a path to a submodule file.

Choosing between imports and full paths¶

You can either:

• use a fully qualified name such as std::option::or_default, or
• import the module or symbol first and use the shorter name.

For example, these styles are both valid:

func main() -> std::date::to_timestamp(@2025-12-16, "UTC")

import std::date::to_timestamp

func main() -> to_timestamp(@2025-12-16, "UTC")

See also¶

• Definitions
• Expressions
• Syntax