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Swiftx is a Swift library containing functional abstractions and extensions to the Swift Standard Library. Swiftx is a smaller and simpler way to introduce pure functional datatypes into any codebase.

For a more full-featured library checkout Swiftz.


Swiftx can be included one of two ways:


  • Drag Swiftx.xcodeproj or Swiftx-iOS.xcodeproj into your project tree as a subproject
  • Under your project's Build Phases, expand Target Dependencies
  • Click the + and add Swiftx
  • Expand the Link Binary With Libraries phase
  • Click the + and add Swiftx
  • Click the + at the top left corner to add a Copy Files build phase
  • Set the directory to Frameworks
  • Click the + and add Swiftx


  • Copy the swift files under Swiftx/Swiftx into your project.


Swiftx provides a number of common data types and abstractions any codebase can utilize.

A small example:

import Swiftx

let str : String? = .Some("Hello ")
let greeting = (+"World") <^> str // .Some("Hello World")

Seamless interaction with existing platform libraries is also possible with minimal effort:

import Foundation
import struct Swiftx.Result

/// result now contains either an array of file paths or the error generated by `NSFileManager`.
let result : Result<[String]> = from({ ep in
    let documentsDirectory : String = (NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as String)
    return (NSFileManager.defaultManager().contentsOfDirectoryAtPath(documentsDirectory, error: ep) as [String]?) ?? []

Swiftx can even help with expressions of nothingness or errors:

import Swiftx

/// We may not be able to do what we said we'd do, but this definition compiles. At runtime, 
/// any code that invokes this function will immediately halt the program.
func provePEqualsNP() -> Proof<P, NP> {
    return undefined()

System Requirements

Swiftx supports OS X 10.9+ and iOS 8.0+.


Swiftx is released under the BSD license.