Normalize path exercise by @vlm

vlm.erl

-module(vlm).

-export([normalize_path/1]).

normalize_path(Path) ->
  Suffix = case string:right(Path, 1) of
             "/" -> "/";
             _   -> ""
           end,

  "/" ++ string:join(lists:reverse(lists:foldl(
    fun(Token,Acc) ->
      case Token of
        "."  -> Acc;
        ".." -> case Acc of []->[];_->tl(Acc) end;
        Tok  -> [Tok|Acc]
      end
    end, [], string:tokens(Path, "/")
  )), "/") ++ Suffix.

z_output.txt

1> vlm:normalize_path("../bar").
"/bar"
2> vlm:normalize_path("/foo/bar").
"/foo/bar"
3> vlm:normalize_path("/foo/bar/../baz").
"/foo/baz"
4> vlm:normalize_path("/foo/bar/./baz/").
"/foo/bar/baz/"
5> vlm:normalize_path("/foo/../../baz"). 
"/baz"