Swift µframework with extensions for the Optional Type

Related tags

Functional Programming swift functional-programming swift-extensions
Overview

OptionalExtensions

CocoaPods Swift 4.0 License MIT

Why?

Swift's Optional is pretty awesome, but it can always get better. This repository is an humble attempt to add some utility methods to it.

Operators

filter: (Wrapped -> Bool) -> Optional<Wrapped>

let number: Int? = 3

let biggerThan2 = number.filter { $0 > 2 } // .Some(3)

let biggerThan3 = number.filter { $0 > 3 } // .None

mapNil: (Void -> Wrapped) -> Optional<Wrapped>

let number: Int? = 3
number.mapNil { 2 } // .Some(3)

let nilledNumber: Int? = nil
nilledNumber.mapNil { 2 } // .Some(2)

flatMapNil: (Void -> Optional<Wrapped>) -> Optional<Wrapped>

let number: Int? = 3
number.flatMapNil { .Some(2) } // .Some(3)

let nilledNumber: Int? = nil
nilledNumber.flatMapNil { .Some(2) } // .Some(2)

then: (Wrapped -> Void) -> Void (similar to [T]'s forEach)

let number: Int? = 3
number.then { print($0) } // prints "3"

let nilledNumber: Int? = nil
nilledNumber.then { print($0) } // print won't be called

maybe: U -> (Wrapped -> U) -> U (similar to Haskell's maybe)

let number: Int? = 3
number.maybe(100) { $0 + 1 } // 4

let nilledNumber: Int? = nil
nilledNumber.maybe(100) { $0 + 1 } // 100

onSome: (Wrapped -> Void) -> Optional<Wrapped> (injects a side effect in the .Some branch)

let number: Int? = 3
let sameNumber = number.onSome { print($0) } // prints "3" & returns .Some(3)

let nilledNumber: Int? = nil
let sameNilledNumber = nilledNumber.onSome { print($0) } // .None

onNone: (Void -> Void) -> Optional<Wrapped> (injects a side effect in the .None branch)

let number: Int? = 3
let sameNumber = number.onNone { print("Hello World") } // .Some(3)

let nilledNumber: Int? = nil
let sameNilledNumber = nilledNumber.onNone { print("Hello World") } // prints "Hello World" & returns .None

isSome: Bool

let number: Int? = 3
let isSome = number.isSome // true

let nilledNumber: Int? = nil
let isSome = nilledNumber.isSome // false

isNone: Bool

let number: Int? = 3
let isSome = number.isNone // false

let nilledNumber: Int? = nil
let isSome = nilledNumber.isNone // true

Setup

Carthage:

github "RuiAAPeres/OptionalExtensions"

CocoaPods:

pod "OptionalExtensions"

Manually:

Grab the OptionalExtensions.swift file and drop it in your project.

Contributing

We will gladly accept Pull Requests with new methods or improving the ones that already exist. Documentation, or tests, are always welcome as well. ❤️

License

OptionalExtensions is licensed under the MIT License, Version 2.0. View the license file

Copyright (c) 2015 Rui Peres

Comments
  • Sugary syntax version

    Sugary syntax version

    This is not an issue!

    I'm just interested in your opinion of the code below, it adds no additional functionality, hence, not an issue. As an exercise for my own entertainment, I've created a version of the extension that utilises as much sugary syntax as I could muster (using single expressions per function and using if case syntax when apt, etc).

    Your original is written in a clear, explicit style which is easy to decipher, the version below is undoubtedly more cryptic (one thing I do like is that each function contains one expression and one return statement, but it is arguable how important that is). I think the versions of onSome and onNone would fit with the current style, but the others are a bit of a departure.

    Anyway, I thought I'd throw it out there to see what you thought.

    All the best, Al

    
public extension Optional {
    func filter(@noescape predicate: Wrapped -> Bool) -> Optional {
        return map(predicate) == .Some(true) ? self : .None
    }

    func replaceNil(with replacement: Wrapped) -> Optional {
        return self ?? replacement
    }

    func apply(@noescape f: Wrapped -> Void) {
        if case let wrapped? = self { f(wrapped) }
    }

    func onSome(@noescape f: Wrapped -> Void) -> Optional {
        apply(f)
        return self
    }

    func onNone(@noescape f: Void -> Void) -> Optional {
        if isNone { f() }
        return self
    }

    var isSome: Bool {
        return map { _ in true } ?? false
    }

    var isNone: Bool {
        return !isSome
    }
}
    enhancement 
    opened by alskipp 16
  • Refactoring tests for better readability

    Refactoring tests for better readability

    I use tests as to understand what a project does - this is a refactor to make that understanding easier.

    Using the given / when / then naming convention, as well as (when possible) one assert per test.

    After doing this refactor, reading over the tests gives me a good idea of what the extensions do. (and on that note I'm wondering if "maybe" expresses what it does... but yet to find a better name):

    screen shot 2016-01-12 at 11 08 37

    opened by gergelyorosz 7
  • Lower deployment requirements

    Lower deployment requirements

    Hey!

    Optional extensions look great, thank you for them!

    This PR lowers deployment targets to following:

    • iOS 8
    • OS X 10.10
    • tvOS 9.0
    • watchOS 2.0

    There does not seem any particular reason not to support those.

    opened by DenTelezhkin 1
  • Added tests

    Added tests

    I wanted to get the tests working using just one Xcode scheme, but struggled to get that working 😕 The OptionalExtensionsTests scheme has been made public, so it should work as expected.

    opened by alskipp 0
  • Adds ReadMe examples as HeaderDocs

    Adds ReadMe examples as HeaderDocs

    I found this convenient to have the examples ready to hand, especially before I wrapped my head around it.

    I also added a compactMapNil for iOS 9.3+, if you like that.

    opened by AmitaiB 0
Owner
Rui Peres
Software Engineer 🛠 | Ultra Trail Runner 🏃‍♂️🏔 "Technology as a means to an end 🚀"
Rui Peres
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