Comment author: administrator

type t = string option;;

type t = string option

let (f : t -> string) = function

  None -> ""
| Some v -> v;;

val f : t -> string =

let g ?opt () = f opt;;

val g : ?opt:Uncaught exception: File "typing/printtyp.ml", line 0,
characters
6494-6506: Assertion failed

The same message was printed when trying to compile the code.
Perhaps a better error message could be used?

Indeed. Due to the structure of the compiler, it would difficult to
get the correct type printed, but I changed it so as to have partial type
information (and no error).

let g ?opt () = f opt;;

val g : ?opt: -> unit -> string

The only way to have the system print the correct type is to write a module
signature... (A type constraint would not do, since it propagates
abbreviation.)

Jacques Garrigue

Comment author: administrator

Partially fixed by Jacques on 2000-06-12.