Created
March 31, 2015 17:28
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//: Sample based on Function Composition snippet from objc.io: http://www.objc.io/snippets/2.html | |
import Foundation | |
func getContents(url: String) -> String { | |
return NSString(contentsOfURL: NSURL(string: url)!, encoding: NSUTF8StringEncoding, error: nil)! as String | |
} | |
func lines(input: String) -> [String] { | |
return input.componentsSeparatedByCharactersInSet(NSCharacterSet.newlineCharacterSet()) | |
} | |
// WITHOUT COMPOSITION --------------------------------------------------------------------------------------- | |
let linesInURL = { url in count(lines(getContents(url))) }("http://www.objc.io/books") | |
// CASE A (process from right to left) ----------------------------------------------------------------------- | |
infix operator <<< { associativity left } | |
func <<< <A, B> (f: A -> B, x: A) -> B { | |
return f(x) | |
} | |
func <<< <A, B, C> (f: B -> C, g: A -> B) -> (A -> C) { | |
return { x in f(g(x)) } | |
} | |
let linesInURL2 = (count <<< lines <<< getContents)("http://www.objc.io/books") | |
let linesInURL3 = count <<< lines <<< getContents <<< "http://www.objc.io/books" | |
// CASE B (process from left to right) ----------------------------------------------------------------------- | |
infix operator >>> { associativity left } | |
func >>> <A, B> (s: A, f: A -> B) -> B { | |
return f(s) | |
} | |
func >>> <A, B, C> (f: A -> B, g: B -> C) -> (A -> C) { | |
return { x in g(f(x)) } | |
} | |
let linesInURL4 = "http://www.objc.io/books" >>> getContents >>> lines >>> count | |
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