PDXErlang intersection implementation w/ Nick

gistfile1.erl

-module(intersection).
-compile(export_all).

intersection(ListA, ListB) ->
  intersection([], ListA, ListB).

intersection(Acc, [], ListB) ->
  Acc;

intersection(Acc, ListA, ListB) ->
  [A|Rest] = ListA,
  Acc1 = case match(A, ListB) of
    true  -> [A|Acc];
    false -> Acc
  end,

  intersection(Acc1, Rest, ListB).


match(X, []) ->
  false;
match(X, [Y|Rest]) when X == Y ->
  true;
match(X, [Y|Rest]) ->
  match(X, Rest).

Clever. I like the decomposition. Worth noting that the given lists also have to be sorted.