ichpuchtli

// [B](f: (A) ⇒ [B]): [B]  ; Although the types in the arrays aren't strict (:
function flatMap<T, U>(array: T[], mapFunc: (x: T) => U[]) : U[] {
    return array.reduce((cumulus: U[], next: T) => [...mapFunc(next), ...cumulus], <U[]> []);
}