Indexable

Defines the exact canonical read indexing protocol used by `Base[Index]`.

Sn is under heavy development. This reference includes the intended 1.0 design; features may be incomplete in the current compiler. Read the status →

Module std.collections

import std.collections;

Public declaration contracts and authored examples. A page can document several related symbols. Implementation bodies are excluded.

Indexable

pub concept Indexable<Self>

Defines the exact canonical read indexing protocol used by Base[Index].

Satisfaction is structural and compile-time-only. The operation returns an element place rather than copying an item, allocates nothing, and remains responsible for its own bounds policy.

Example

module example.indexable;
from std.collections import Vector;
fn Main() -> i32 {
    var Values = Vector<i32>();
    if Values.TryPush(4) is .Err { Error = Failure } {
        return Failure.Value;
    }
    Values[0] = 9;
    let ReadOnly: readonly i32[] = Values.AsSlice();
    if ReadOnly[0] != 9 {
        return 1;
    }
    return 0;
}

WritableIndexable

pub concept WritableIndexable<Self>

Extends canonical indexing with writable element-place access. Self: Mutable source type satisfying both exact At requirements.

Documentation snapshot: October 24, 2026 About versions ↗