Language

This page is the short operational reference. Full semantics are in docs/SPEC.md. Verified examples live under examples/, especially 037_language_tour.a7.

Program shape

Top-level bindings and functions use ::. Functions use fn, explicit ret, and typed parameters.

io :: import "std/io"

greet :: fn(name: string) {
    io.println("Hello, {}!", name)
}

main :: fn() {
    greet("A7")
}

Declarations

• Top-level constants and functions: name :: value
• Mutable locals with inference: count := 0
• Explicit type: count: i32 = 0

Control flow

Use if, while, for, break, continue, and match. A7 source recursion is rejected at compile time. Rewrite recursive algorithms with loops, index worklists, or explicit stacks.

sum_to :: fn(n: usize) usize {
    total: usize = 0
    i: usize = 0
    while i <= n {
        total = total + i
        i = i + 1
    }
    ret total
}

Indexed iteration:

for index, value in items {
    // index is usize
}

Types

Examples and docs may use:

• Integers and floats
• bool, char, strings
• Fixed arrays and slices
• Structs, enums, and untagged unions
• References with nil checks
• Simple generic functions and structs

Reserved or incomplete areas belong in Status, not in examples that pretend they are complete.

Imports

Standard library imports use virtual module paths:

io :: import "std/io"
math :: import "std/math"

Local file imports are being extended for multi-file programs. Generated Zig remains single-file output.

Hard rules

• A7 source recursion is rejected. Use loops, index worklists, or explicit stacks.
• Use usize for sizes, lengths, capacities, and indexes.
• Reserve isize for signed pointer-sized offsets and position differences.
• new [N]T is rejected. Use stack arrays or slices.
• Public reference syntax does not expose address-of or dereference operators. Pass lvalues directly to ref parameters.