Module Async.Sexp.Sexp_maybe

If sexp_of_t fails, it returns Error rather than raising. You can convert values of this type to and from sexp in processes that can or cannot parse the underlying sexp in any combination and still recover the original value. Also, the Error case contains a human-readable description of the error.

A common use case is to parse most of a sexp even when some small part fails to parse, e.g.:

      type query =
        | Start of Initial_config.t Sexp_maybe.t
        | Stop of  Reason_to_stop.t Sexp_maybe.t
      [@@deriving sexp]
    

If Reason_to_stop.t_of_sexp fails, you can still tell it was a Stop query.