[mbucc]

The benefit I see is that (at least in Erlang) pattern matching combines pre-condition asserts with programming the sunny path. For example,

   "/" ++ X = HttpRequest:get(path).

will crash if PATH_INFO doesn't include leading slash. Writing just the sunny path and getting asserts "for free" (without any clutter) is a fun way to program.

I also find that statement very readable.

BTW, here's some Java code that does the same thing:

  String Path;
  if (HttpRequest.getPathInfo().startsWith("/")) {
     Path = HttpRequest.getPathInfo().substring[1:];
  } else {
     String emsg = "no match of right hand side value \"%s \"";
     throw new IllegalStateException(emsg.format(HttpRequest.getPathInfo());
  }