A small example in creating string slugs.

slug.erl

-module(slug).
-compile(export_all).

test() -> [
        {slugify("Hello World"), "hello-world"},
        {slugify("                      HELLO                    *(^&)*(&* WORLD                 "), "hello-world"}
    ].

slugify(String) ->
    slugify(String, []).

slugify([], Acc) -> Out = case Acc of [45 | T] -> T; _ -> Acc end, lists:reverse(Out);
slugify([H | Tail], Acc) ->
    NewH = case H of
        H when H > -1, H < 10 -> H; %% Numbers stay the same
        H when H > 96, H < 123 -> H; %% lowercase stays the same
        H when H > 64, H < 91 -> H + 32; %% upercase is made lowercase
        _ -> 45 %% everything else gets replaced with an '-'
    end,
    NewAcc = case {NewH, Acc} of
        {45, []} -> []; %% Prevent leading '-' characters
        {45, [45 | _ ]} -> Acc; %% Prevent dupe '-' characters
        _ -> [NewH | Acc]
    end,
    slugify(Tail, NewAcc).