Modules

A file is a module. Its declarations are private unless marked pub:

geometry.resid

type Point = { Int x; Int y; };

pub Int dist2(Point a, Point b) {
    Int dx = a.x - b.x;
    Int dy = a.y - b.y;
    return dx * dx + dy * dy;
}

Import it by path, relative to the importing file:

import "geometry.resid";             // every pub name
import "geometry.resid" (dist2);     // only these
import "geometry.resid" as G;        // qualified: G.dist2(a, b)

Each module keeps its own names. If two modules you import both export a parse, import them as and qualify the use: json.parse(s), toml.parse(s). A plain parse(s) would be ambiguous and is an error (E0223); a function of your own named parse wins over both.

An import that is not found beside the importing file is looked up in the standard library (lib/ of the Resid installation), so import "crypto.resid"; works anywhere. A missing module is an error (E0221).

An import can also be attenuated: the module and everything it imports run with at most the listed capabilities, even if it asks for more:

import "http.resid" @requires(network);

See Capabilities and Modules in the reference.