Doing Combination in Erlang ref: http://panduwana.wordpress.com/2010/04/21/combination-in-erlang/

sample.erl

-module(sample).
-export([combos/1, combos/2]).

combos(1, L) -> [[X] || X <-L];
combos(K, L) when K == length(L) -> [L];
combos(K, [H|T]) ->
    [[H | Subcombos] || Subcombos <- combos(K-1, T)]
    ++(combos(K, T)).
 
combos(L) ->
    lists:foldl(
        fun(K, Acc) -> Acc++(combos(K, L)) end,
        [[]],
        lists:seq(1, length(L))
    ).