Fixed Primitives

Fixed<S> — a column adapter that enforces the count == capacity invariant from construction onward, giving an always-full array over any Store / Buffer column.

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Quick Start

Fixed<S> wraps a storage column and proves, at the type level, that every slot is initialized: count == capacity is established at construction and preserved by the surface. There is no append or remove that could leave a hole — the only writes are in place (subscript, swap), so downstream code never has to handle the partially-filled case.

The pinned constructors build the canonical non-growable heap column for you and infer the column type, so the common case needs no column spelling:

import Fixed_Primitives
import Index_Primitives
import Tagged_Primitives_Standard_Library_Integration
import Ordinal_Primitives_Standard_Library_Integration

// Build three slots, each initialized at construction — `count == capacity` is
// structural, so there is never a partially-filled state to handle.
var grid = Fixed(repeating: 0, count: Index<Int>.Count(3))

grid[0] = 10            // in-place replacement — the only kind of write Fixed allows
grid[2] = 30
grid.swap(at: 0, with: 2)

print(grid[0])                                   // 30
print(grid.count == grid.capacity)               // true  — always-full, by construction
print(grid.freeCapacity == Index<Int>.Count(0))  // true  — no slot left to grow into

The two *_Standard_Library_Integration imports come from swift-tagged-primitives and swift-ordinal-primitives; they let typed indices accept plain integer literals (grid[0], Index<Int>.Count(3)). Add those packages alongside this one to use that syntax.

Fixed is conditionally Copyable and Sendable exactly when its backing column is, and it adds no storage of its own — the invariant is structural, not bookkeeping.

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Installation

dependencies: [
    .package(url: "https://github.com/swift-primitives/swift-fixed-primitives.git", branch: "main")
]

.target(
    name: "App",
    dependencies: [
        .product(name: "Fixed Primitives", package: "swift-fixed-primitives"),
    ]
)

The package is pre-1.0 — depend on branch: "main" until 0.1.0 is tagged. Requires Swift 6.3.1 and macOS 26 / iOS 26 / tvOS 26 / watchOS 26 / visionOS 26 (or the matching Linux / Windows toolchain).

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Architecture

Two library products over the Store / Buffer column primitives.

Product	Target	Purpose
Fixed Primitive	Sources/Fixed Primitive/	The Fixed<S> namespace and base type — the always-full column adapter and its Fixed.Error.
Fixed Primitives	Sources/Fixed Primitives/	Umbrella — the Collection / Span / Equation / Hash conformances and the pinned bounded-heap-column constructors; re-exports Fixed Primitive.

Foundation-free.

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Platform Support

Platform	Status
macOS 26	Full support
Linux	Full support
Windows	Full support
iOS / tvOS / watchOS / visionOS	Supported

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Community

License

Apache 2.0. See LICENSE.md.