Writing Your Own Modules

A module is a .co file of functions, structs, and constants. Your modules are always qualified — importing one reserves a single bare name (the prefix), and everything inside is reached through it:

--- geometry.co ---
struct Circle [r]

fn circle_area[c]
    return 3.14159 * c.r * c.r

--- main.co ---
use geometry

c = geometry.Circle[2.0]
log[geometry.circle_area[c]]

Subdirectories map through slashes (use myapp/utils → utils.helper[...]), dots also work for view files (use views.home), and aliases apply as everywhere (use geometry as g → g.circle_area[...]).

The asymmetry with the standard library is deliberate: the bare namespace belongs to the language. Stdlib names are hand-curated and frozen-or-slow-moving; your module can export a thousand names and take none of anyone's vocabulary — the import costs exactly one word, the prefix. That's also why two modules can never collide: same trailing name, different aliases, done.

Next: saying what a function must do — and having Crow prove it.