使用reduce来实现map和filter功能
let a = [1,2,3]let b = a.reduce(0, combine: +)extension Array {func mMap(transform: Element -> U) -> [U] {
return reduce([], combine: { $0 + [transform($1)]})
}
func mFilter (includeElement: Element -> Bool) -> [Element] {
return reduce([]) {
includeElement($1) ? $0 + [$1] : $0
}
}
}
let c = a.mMap({ $0 + 2})
let d = a.mFilter({ $0 > 2})
print(c)
print(d)
