Modules

A Tantu program is a set of sibling *.tn files in one directory. import name makes the members of name.tn available under a name. prefix.

Playground note

The playground has a single editor, so the multi-file examples on this page are marked so; run them locally with python -m tantu run main.tn. Everything else in these docs runs in the browser.

# mathlib.tn
fn square(n: Int) -> Int:
    n * n

let answer = 42

# main.tn
import mathlib

fn main() -> Unit:
    print(mathlib.square(5))   # 25
    print(mathlib.answer)      # 42

How a program is assembled

Running tantu run main.tn:

1. Discovers the import graph starting from the root file.
2. Checks each module in dependency order (a module is checked after everything it imports).
3. Links every module's globals into one flat table.
4. Initializes each module's top-level bindings, dependencies first.
5. Calls the root module's main().

What you can import

In v1, imports are value-only: you can use another module's functions and its top-level let bindings (and the nominal types in their signatures). Sharing enums, structs, and their constructors across modules is deferred past v1; define those in the module that uses them.

Errors

Import mistakes are caught at compile time:

• An import cycle is E0130.
• A missing module file is E0131.
• Accessing a name the module doesn't define is E0132.
• Using a module name as a value (instead of module.member) is E0133.

import needs real files on disk, so it isn't available for stdin or the REPL (E0134).