Swiftz is a Swift library for functional programming.
It defines functional data structures, functions, idioms, and extensions that augment the Swift standard library.
For a small, simpler way to introduce functional primitives into any codebase, see Swiftx.
Swiftz draws inspiration from a number of functional libraries and languages. Chief among them are Scalaz, Prelude/Base, SML Basis, and the OCaml Standard Library. Elements of the library rely on their combinatorial semantics to allow declarative ideas to be expressed more clearly in Swift.
Swiftz is a proper superset of Swiftx that implements higher-level data types like Arrows, Lists, HLists, and a number of typeclasses integral to programming with the maximum amount of support from the type system.
To illustrate use of these abstractions, take these few examples:
Lists
import struct Swiftz.List //: Cycles a finite list of numbers into an infinite list. let finite : List<UInt> = [1, 2, 3, 4, 5] let infiniteCycle = finite.cycle() //: Lists also support the standard map, filter, and reduce operators. let l : List<Int> = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] let twoToEleven = l.map(+1) // [2, 3, 4, 5, 6, 7, 8, 9, 10, 11] let even = l.filter((==0) • (%2)) // [2, 4, 6, 8, 10] let sum = l.reduce(curry(+), initial: 0) // 55 //: Plus a few more. let partialSums = l.scanl(curry(+), initial: 0) // [0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55] let firstHalf = l.take(5) // [1, 2, 3, 4, 5] let lastHalf = l.drop(5) // [6, 7, 8, 9, 10]Semigroups and Monoids
let xs = [1, 2, 0, 3, 4] import protocol Swiftz.Semigroup import func Swiftz.sconcat import struct Swiftz.Min //: The least element of a list can be had with the Min Semigroup. let smallestElement = sconcat(Min(2), t: xs.map { Min($0) }).value() // 0 import protocol Swiftz.Monoid import func Swiftz.mconcat import struct Swiftz.Sum //: Or the sum of a list with the Sum Monoid. let sum = mconcat(xs.map { Sum($0) }).value() // 10 import struct Swiftz.Product //: Or the product of a list with the Product Monoid. let product = mconcat(xs.map { Product($0) }).value() // 0Arrows
import struct Swiftz.Function import struct Swiftz.Either //: An Arrow is a function just like any other. Only this time around we //: can treat them like a full algebraic structure and introduce a number //: of operators to augment them. let comp = Function.arr(+3) • Function.arr(*6) • Function.arr(/2) let both = comp.apply(10) // 33 //: An Arrow that runs both operations on its input and combines both //: results into a tuple. let add5AndMultiply2 = Function.arr(+5) &&& Function.arr(*2) let both = add5AndMultiply2.apply(10) // (15, 20) //: Produces an Arrow that chooses a particular function to apply //: when presented with the side of an Either. let divideLeftMultiplyRight = Function.arr(/2) ||| Function.arr(*2) let left = divideLeftMultiplyRight.apply(.Left(4)) // 2 let right = divideLeftMultiplyRight.apply(.Right(7)) // 14Operators
See Operators for a list of supported operators.
To add Swiftz to your application:
Using Carthage
- Add Swiftz to your Cartfile
- Run
carthage update - Drag the relevant copy of Swiftz into your project.
- Expand the Link Binary With Libraries phase
- Click the + and add Swiftz
- Click the + at the top left corner to add a Copy Files build phase
- Set the directory to
Frameworks - Click the + and add Swiftz
Using Git Submodules
- Clone Swiftz as a submodule into the directory of your choice
- Run
git submodule init -i --recursive - Drag
Swiftz.xcodeprojorSwiftz-iOS.xcodeprojinto your project tree as a subproject - Under your project's Build Phases, expand Target Dependencies
- Click the + and add Swiftz
- Expand the Link Binary With Libraries phase
- Click the + and add Swiftz
- Click the + at the top left corner to add a Copy Files build phase
- Set the directory to
Frameworks - Click the + and add Swiftz
Using Swift Package Manager
- Add Swiftz to your
Package.swiftwithin your project'sPackagedefinition:
let package = Package( name: "MyProject", ... dependencies: [ .package(url: "https://github.com/typelift/Swiftz.git", from: "0.0.0") ... ], targets: [ .target( name: "MyProject", dependencies: ["Swiftz"]), ... ] )Swiftz supports OS X 10.9+ and iOS 8.0+.
Swiftz is released under the BSD license.