Modules and packages

Each .fb file is a module. What it declares is private to it unless it’s marked Public, and another file uses it with Import. There’s no textual include.

A package is a folder with a project.toml, which names it, and its main file, main.fb, whose top-level code is the program. Its other files are modules named by the package’s name and their paths: combat.fb in the package arena is arena.combat.

[project]
name = "arena"
version = "0.1.0"

Import std.core

Public Struct Fighter
    Public Field name: String
    Public Field attack: Int
End Struct

Public Function Duel(a: Fighter, b: Fighter): String
    Return a.attack >= b.attack ? a.name : b.name
End Function

Function Secret(): Int => 42            // only combat.fb sees this

Import std.core
Import arena.combat

Local winner = Duel(Fighter("Ada", 7), Fighter("Grace", 9))
Print("{winner} wins")

Grace wins

fb run in the folder builds the package and runs it.

Imports

Import std.core                     // a module of std's
Import std.collections              // a folder: each of its files' modules
Import std.math As M                // only as M.Vec3, M.Lerp
From std.text.regex Import Regex    // only the names it lists

Local v = M.Vec3(1, 2, 3)
Print(v, Try Regex("a+").IsMatch("caaat"))

A package’s dependencies go in its project.toml’s [dependencies], by their folders for now; a package registry comes later. The modules and packages guide has the rest. That’s the tour: next, the tutorial builds a game, a tool, and a web service, the docs go deeper on each part, and std’s reference has every module.