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[Caml-list] format type
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Date: 2002-11-03 (10:31)
From: Cezary Kaliszyk <ck189400@z...>
Subject: [Caml-list] format type
I'm trying to write a function that takes a format and a function and
applies some (got from elsewere) arguments to the function.

All works ok for nonempty format.
 myfun "%c%s"
is of type:
 (char -> string -> unit) -> unit

IS IT POSSIBLE (with the current implementation) of the format type type
checking to pass some format that would require a (unit -> unit)

Ie: I'd like:
 myfun ""
to be of type:
 (unit -> unit) -> unit

If such construnction is not possible at all perheapes some new
identifier "%?" should be added to fromat type type checking. This
argument would take exacly one argument of type unit.

My current implementation:
let receive (fmt : (('a, unit, unit) format)) (f : 'a) : unit =
  let fmt_str = string_of_format fmt in
  let rec parse f i =
    match fmt.[i] with
        I call recursively:
          parse (lazified ((forced f) with applied arg)) (i + 1)
  Obj.magic (parse (fun () -> f) 0) ()

The only known workaround for me for now is to pass "%t" and
make my function not (unit -> unit) but ('a -> unit). 

Writing code with changed types just for the sake of the language is
very bad. And with "%t" 'a seems to be (unit -> unit).

Cezary Kaliszyk