rps.erl

-module(rps).
-export([tournament/2]).
beat(rock) ->
    paper;
beat(scissors) ->
    rock;
beat(paper) ->
    scissors.

lose(rock)->
    scissors;
lose(scissors) ->
    paper;
lose(paper) ->
    rock.

result(Left,Right)->
    BeatRight=beat(Right),
    case Left == Right of 
	true -> 0;
	false -> case BeatRight == Left of 
		     true -> 1;
		     false -> -1
		     end
    end.
% using the zip_with defined before

tournament(Xs,Ys) ->			 
    Results = hofs:zip_with(fun result/2, Xs,Ys),
    lists:sum(Results).