flatten

Lib.flatten : 'a list list -> 'a list

Removes one level of bracketing from a list.

An invocation flatten [[x11,...,x1k1],...,[xn1,...,xnkn]] yields the list [x1,...,x1k1,...,xn1,...,xnkn].

Failure

Never fails.

Example

> flatten [[1,2,3],[],[4,5]];
val it = [1, 2, 3, 4, 5]: int list

> flatten ([[[]]] : int list list list);
val it = [[]]: int list list