src/hope_list.erl

   1 -module(hope_list).
   2
   3 -export_type(
   4     [ t/1
   5     ]).
   6
   7 -export(
   8     [ unique_preserve_order/1
   9     ]).
  10
  11
  12 -type t(A) ::
  13     [A].
  14
  15
  16 -spec unique_preserve_order(t(A)) ->
  17     t(A).
  18 unique_preserve_order(L) ->
  19     AppendIfNew =
  20         fun (X, Xs) ->
  21             case lists:member(X, Xs)
  22             of  true  -> Xs
  23             ;   false -> Xs ++ [X]
  24             end
  25         end,
  26     lists:foldl(AppendIfNew, [], L).