Created
July 13, 2014 01:51
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Swift: For a function that takes two arguments, return equivalent function with argument order reversed (like Haskell "flip")
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| // For a function that takes two arguments, return equivalent | |
| // function with argument order reversed. | |
| // | |
| // (Like "flip" in Haskell prelude) | |
| func flip<A, B, T>(f: (A, B) -> T) -> (B, A) -> T { | |
| return { (b: B, a: A) -> T in return f(a, b) } | |
| } | |
| // Examples | |
| func subtract(a: Int, b: Int) -> Int { | |
| return a - b | |
| } | |
| let flippedSubtract = flip(subtract) | |
| let result1 = subtract(10, 3) // 7 | |
| let result2 = flippedSubtract(10, 3) // -7 | |
| func concat(s1: String, s2: String) -> String { | |
| return s1 + s2 | |
| } | |
| let reverseConcat = flip(concat) | |
| let result3 = concat("Hello, ", "world!") // "Hello, world!" | |
| let result4 = reverseConcat("Hello, ", "world!") // "world!Hello, " |
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