string - ocaml の奇妙な構文エラー

Question

Ocaml を使い始めたばかりなのですが、理解できない奇妙な構文エラーが発生しました。ここに私のプログラムがあります:

let out x = Printf.printf " %s \n" x 
let _ = try
  while true do
    let line = input_line stdin in 
     begin
    match (Str.split (Str.regexp " ") line) with
            ["commit";code] -> out code;
            | ["diff"; _; before; after] -> out before;
        out after;
          let rec f (xpath: string list) : ( string list ) =
           (match  Str.split (Str.regexp "/") xpath  with 
                     | _ ::rest -> out (String.concat "/" rest)
                     | _ -> []
           )
            | _ -> ()
     end
   done
with
  End_of_file -> ()