Import styles
Zolo offers two main styles for accessing names from a module: qualified
access (lib_demo::add(...)) and imported access (add(...) after use).
Each has its place.
Use imported access when a name is called frequently and there is no risk of name collision in the scope. The example below mixes single import and list import in the same file:
add comes from use lib_demo::add; sub and get_pi arrive via the list.
Both forms work together in the same file.
// Feature: qualified access vs. imported name — when to use each
// Syntax: `lib::foo()` (qualified) vs. `foo()` (after `use`)
// When to use:
// - qualified: module is large and names are generic
// (e.g. `time::now`, `math::sqrt`); makes origin clear
// - imported: name is unique and used a lot; reduces noise
mod lib_demo
// Imports only `add` — uses `add(...)` directly.
use lib_demo::add
// SKIP: `use lib_demo` alone (for qualified access elsewhere in
// the file) is rejected by the loader. Pull every name explicitly.
use lib_demo::{sub, get_pi}
fn main() {
// Imported: call directly.
let s = add(10, 5)
print("add direct = {s}")
// expected: add direct = 15
let d = sub(10, 5)
print("sub = {d}")
// expected: sub = 5
print("pi = {get_pi()}")
// expected: pi = 3.14159
}
When a program uses several modules, declare one mod per file and combine
use in whichever style is clearest for each module:
use lib_demo::greet (single) and use lib_demo::{add, sub, VERSION} (list)
coexist without conflict.
// Feature: import from more than one module in the same file
// Syntax: multiple `mod` + `use` declarations at the top
// When to use: real programs almost always combine several modules;
// declare each `mod` once at the entry-point and use them at call sites.
// Loads both files alongside: `lib_demo.zolo` and
// `multi-file/helpers.zolo` (the latter we would reference via a
// relative path embedded in the multi-file folder example). Here we
// just re-use lib_demo.
mod lib_demo
// You can mix forms (single + list). The bare `use lib_demo` form
// for qualified access is currently rejected by the loader; pull
// the constant explicitly instead.
use lib_demo::greet // single
use lib_demo::{add, sub, VERSION} // list
fn main() {
greet("multi")
// expected: Hello, multi!
print("add = {add(2, 3)}")
print("sub = {sub(7, 4)}")
print("VERSION = {VERSION}")
// expected:
// add = 5
// sub = 3
// VERSION = 1.0.0
}
The trade-off comparison example shows all three scenarios in one place — wildcard for native plugins, list for user modules, and direct import for frequently used names:
For user .zolo modules, prefer the list {a, b, c}. Reserve the wildcard
::* for native plugins (winit, wgpu, binary...).
// Feature: tradeoffs between `use foo::*`, list, and qualification
// Syntax: three variants — side-by-side comparison
// When to use: see the guide below for each scenario.
// === Scenario 1: many names from the same module, all from a plugin ===
// Native-plugin import -> wildcard via `use plugin` is OK and idiomatic.
//
// use plugin winit::*
// use plugin wgpu::*
//
// === Scenario 2: you need a few specific functions ===
// Named list -> shows exactly what is in use.
//
// use lib_demo::{add, sub, greet}
//
// === Scenario 3: rare use, or names may collide ===
// Qualified access -> keeps origin explicit.
//
// use lib_demo
// ...
// lib_demo::add(1, 2)
mod lib_demo
// Mixing strategies in a single file. Bare `use lib_demo` (for
// qualified access elsewhere) is rejected by the current loader,
// so pull the occasional name explicitly too.
use lib_demo::greet // called several times -> direct import
use lib_demo::add // occasional, but still imported by name
fn main() {
// Good: direct name (frequent use).
greet("alice")
greet("bob")
greet("carol")
// expected:
// Hello, alice!
// Hello, bob!
// Hello, carol!
let s = add(2, 3)
print("sum = {s}")
// expected: sum = 5
}
Challenge
In the multiple-mods example, add a second dummy mod and use a name from it
alongside the names from lib_demo. Notice how the compiler keeps the two
origins separate.
See also