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Date: Mon, 24 Mar 2014 09:46:19 +0100
From: Alain Frisch <alain@frisch.fr>
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To: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>, 
 Kiselyov Oleg <oleg@okmij.org>
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 OCaml Mailing List <caml-list@inria.fr>
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Subject: Re: [Caml-list] typechecking

On 03/23/2014 01:59 PM, Jacques Garrigue wrote:
> So well, unsound functions are unsound, and you have to live with that.
> In particular _always_ annotate with ground types.

It might be useful to check that the user provides an explicit type for 
the result of input_value and similar functions.  This could be 
implemented in the same way as the new warning on deprecated 
declarations, i.e. with a compiler-recognized attribute on those special 
functions:


  val input_value: in_channel -> 'a
     [@@requires_explicit_type]


The compiler would raise a warning if the call site does not provide 
explicit type information such as:

    let x : ... = input_value ic in ...

or:

   let x = (input_value ic : x) in ...


The notion of "explicit type information" could probably be the same as 
the one used for type propagation, or even a more syntactic criterion.


-- Alain