Swift Functional Programming - Second Edition

Removing duplicates in an array

We can use reduce to remove duplicate elements in an array as follows:

let arrWithDuplicates = [1, 1, 2, 3, 3, 4, 4, 5, 6, 7] let arrWithoutDuplicates = arrWithDuplicates.reduce([]) {     (a: [Int], b: Int) -> [Int] in     if a.contains(b) {         return a     } else {         return a + [b]     } } print(arrWithoutDuplicates) 

The result will be [1, 2, 3, 4, 5, 6, 7], as expected.