A simple rewriting of the uniq command line tool.

uniq.swift

#!/usr/bin/env xcrun swift -F $(xcode-select)/Platforms/MacOSX.platform/Developer/Library/Frameworks

import Foundation

//need to process any arguements here
//
// uniq [-c | -d | -u] [-i] [-f num] [-s chars] [input_file [output_file]]

// MARK: Standard In , Standard Out
func getStandardInput() -> String? {

    let standardInput = NSFileHandle.fileHandleWithStandardInput()
    let input = standardInput.availableData

    return NSString(data: input, encoding: NSASCIIStringEncoding) as String?
}

func writeStandardOutput(out: String){
    let standardOutput = NSFileHandle.fileHandleWithStandardOutput()
    if let data = out.dataUsingEncoding(NSASCIIStringEncoding){
        standardOutput.writeData(data)
    }
}

// MARK: Start Script
let input = getStandardInput()

if input == nil {
    exit(1)
}

//unwrap this since we know input is not nil
var separated = input?.componentsSeparatedByCharactersInSet(NSCharacterSet.newlineCharacterSet())
separated?.removeLast()

func _uniq<T: Equatable>(initial: [T], next: T) -> [T]{
    if initial.last! != next {
                    return initial + [next]
    } else {
        return initial
    }
}

func uniq<T: Equatable>(a: Array<T>) -> Array<T>{
    let tooSmallToSort = a.count < 2
    switch tooSmallToSort {
    case true: return a
    case false: return a.reduce([a.first!], combine: _uniq)
    default: println("Bool is not true or false. I am going crazy")
        return [] 
  }
}

if let separated = separated{
    let results = uniq(separated)
    writeStandardOutput( results.reduce("", { $0 + $1 + "\n"}) )
} else {
    exit(1)
}