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Message-ID: <48BCF2BB.3090507@uibk.ac.at>
Date: Tue, 02 Sep 2008 10:00:59 +0200
From: Christian Sternagel <christian.sternagel@uibk.ac.at>
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To: caml-list@yquem.inria.fr
Subject: `This expression is not a function it cannot be applied'
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X-Spam: no; 0.00; parser:01 sig:01 val:01 struct:01 parser:01 cheers:01 token:01 token:01 abstract:01 ident:01 data:02 expression:02 functional:02 module:03 module:03 

Is there a way to be able to apply something of an abstract data type 
without knowing the internal representation?

E.g., when having the module
module Parser : sig
  type ('a,'tok) t
  val token : ('tok -> 'a option) -> ('a,'tok) t
end = struct
  type ('a,'tok) t = 'tok list -> ('a * 'tok list)
  let token ... = ...
end

I want to be able to apply the result of (token (function Ident s -> 
Some s | None)) to some further input (since it is a parser), however, 
this is not possible since the result type is not functional.

The only way out I see is to `unabstract' the type and give its internal 
representation. Or is there another possibility?

cheers

christian