noeticgarden/pico-nonempty

## Noetic Garden: Picos

Noetic Garden: Picos

Noetic Garden Picos are tiny packages of small, oft-repeated functionality that I carry project to project. Feel free to use them in yours. Picos are tested on Apple OSes, Linux, and Windows.

The Nonempty package includes Nonempty, a wrapper type that you can use to assert that a collection is nonempty.

You can use this type to:

Show to the compiler that a specific collection will not be empty when used. Use the built-in nonempty projection to access useful variants of regular collection API without having to handle optionals, and returning Nonempty wrappers to prove that your edit did not cause the collection to shrink.

Indicate in your interfaces that a nonempty collection is required without having to cause precondition failures when accepting an empty one.

You can use this as its own type, or as a property wrapper to keep accessing the full API of the underlying collection type.

For example:

var numbers = Nonempty(assert: [1, 2, 3, 4])

// Only perform operations that maintain the nonempty property:

numbers.remove(at: 0) // compiler error!
numbers.nonempty.append(5) // works!

let double = numbers.nonempty.map {
    $0 * 2
} // double is a Nonempty<[Int]>!

// Use the nonempty type as a collection itself:
for number in numbers {
    print(number)
}

// … and avoid optionals where possible:
let maybeFirst = numbers.first // Optional<Int>: 1
let first = numbers.nonempty.first // Int: 1

// Use this as a property wrapper:
@Nonempty var newNumbers = numbers
print(type(of: newNumbers)) // Array<Int>

// Access the modified API above via its projected value:
$numbers.append(6)
let last = $numbers.last // Int: 6

Using this Package:

Add this repository as a Swift Package Manager dependency:

.package(url: "https://github.com/noeticgarden/pico-nonempty.git", from: "1.0.0"),

Then, use the Nonempty module:

dependencies: [
    .product(name: "Nonempty", package: "pico-nonempty"),
]

Issues and Support

Use this repository's Issues tab to report issues. Pull requests are welcome with owner review. All support and PR acceptance is best-effort and not guaranteed. Please be kind.

Package Metadata

Repository: noeticgarden/pico-nonempty

Default branch: main

README: README.md