yet better formatting

foo.ml

let rec lexwhile prop inp =
  match inp with
  | c::cs when prop c -> 
    let (tok,rest) = lexwhile prop cs in 
    (c^tok,rest)
  | _ -> ("",inp)
;;
  
let rec lex inp =
  match snd (lexwhile space inp) with
  | [] -> [] 
  | c::cs -> 
    let prop =  
      if alphanumeric(c) then alphanumeric
      else if symbolic(c) then symbolic
      else (fun c -> false)
    in
    let (toktl,rest) = lexwhile prop cs in
    (c^toktl) :: lex rest
;;