Modules

Learning Echo from scratch?

Start with Lesson 8 — Organizing programs. This page is the fuller module write-up.

Split a program across .echo files with export and import. Each file is its own module scope. Full contract: Module Semantics.

Basic Example

Two files in the same directory:

# math.echo

export fn add(a: int, b: int) -> int {
    return a + b;
}

# app.echo

import add from "math";

say(add(2, 3));

Run the entry file (from the directory that contains both files):

elang app.echo

Output

5

How It Works

• Specifiers resolve relative to the importing file: "math", "./math", "lib/math", "../shared".
• Reserved std/… imports load from the Echo install tree (available after pip/pipx install):

import stdOk from "std/meta";

say(stdOk());

Output

true

• Only exported names are visible to importers. Private names stay in the defining module.
• import is not the same as use / use mut (those are function-scope capture / mutation).
• Nested demo in the repo: from a clone at the repo root, elang examples/modules_demo/app.echo prints:

2+3 = 5
6^2 = 36
std ready: true

Common Mistakes

• Expecting math.add(...) dotted namespaces — not supported; bind names with import.
• Pointing elang examples/... at a pipx-only install — examples/ is clone-only.
• Forgetting export on the name you import.

Related

• Module Semantics — full path / cycle / std rules
• Mini Programs
• Std Inventory
• CLI and Execution Model