Dear All,

I am trying to use the Str module to match regular expressions. I want to
return the longest match.

let txt = "ab"
let reg = "a\\|ab"
let _ =
  let b = Str.string_match (Str.regexp reg) txt 0 in
  Str.matched_string txt

After the last line, the string "a" is apparently matched. But I hope that
the result should be "ab". If I reverse the order of the alternatives in
the regular expression, the string "ab" is matched. I don't want the order
of the alternatives to matter. What am I doing wrong? What can I do to
match the longest substring?

Thanks

Tom