Version française
Home     About     Download     Resources     Contact us    
Browse thread
[Caml-list] mystified by typing of optional arguments
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: -- (:)
From: Francois Thomasset <francois.thomasset@i...>
Subject: Re: [Caml-list] mystified by typing of optional arguments
> Hi all,
> The following example mystifies me
> 
> let f ?opt x =
>    match opt with
>    | None -> x
>    | Some dx -> x + dx
> 
> let g x = x + 1
> 
> 
> let h1 = function
>    | 0 -> [g]
>    | _ -> [f; g]
> 
> 
> let h2 = function
>    | _ -> [f; g]
> 
> 
> h1 is typable but not h2.
> Why is that ?
You cant' type [f;g] either !
# [ f ; g ];;
This expression has type int -> int but is here used with type
  ?opt:int -> int -> int
While [g;g] is a list of funs
FT



-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners