open FParsec

​

let parseBy p str =

  match run p str with

   | Success (res, _, _) -> res

   | Failure (msg, _, _) -> failwithf "%s" msg

​

let parseSexpr, parseSexprRef = createParserForwardedToRef()

parseSexprRef := between (pchar '(') (pchar ')') (sepEndBy (parseSexpr <|> pint32) spaces)

printf "%A" (parseBy parseSexpr "(1 2 3)")