Re: [Caml-list] Teaching bottomline, part 3: what should improve.

From: David Thomas <david_hd@yahoo.com>
To: OCaml <caml-list@inria.fr>
Subject: Re: [Caml-list] Teaching bottomline, part 3: what should improve.
Date: Tue, 22 May 2007 19:46:22 -0700 (PDT)	[thread overview]
Message-ID: <319338.70616.qm@web30506.mail.mud.yahoo.com> (raw)
In-Reply-To: <1179875804.17533.33.camel@rosella.wigram>

Would it be possible for this to be an option?  I
mean, it seems like the information is at least
available on another pass through the code.  Twice the
compilation time in some cases will typically win out
over minutes-to-hours trying to figure out where it
inferred THAT.

--- skaller <skaller@users.sourceforge.net> wrote:

> On Tue, 2007-05-22 at 18:10 -0400, David Teller
> wrote:
> 
> > * Error messages of the type system are somewhat
> obscure. The reflex of
> > many students is "OCaml wants it to be of type
> XXX", rather than "there
> > is a contradiction in what I wrote". It would be
> nice if there was a way
> > to ask OCaml to display additional information on
> type errors.
> 
> This is a long standing peeve of mine. Lets face it:
> Ocaml just lies.
> If it has inferred a type, then finds a
> contradiction, it should
> report both the location of the contradication AND
> all of the source
> lines that contributed to the inference.
> 
> I understand that is may be hard, if not impossible,
> to implement,
> as it would require a unification engine that could
> manage
> source references in parallel with deductions ..
> still the information
> IS available originally.
> 
> I bet this would be an interesting and valuable PhD
> project,
> and, IMHO, without it type inferencing languages are
> useless
> in industry. Type errors in Ocaml code are very
> common for the
> simple reason they're just about the only error you
> can make :)
> 
> 
> -- 
> John Skaller <skaller at users dot sf dot net>
> Felix, successor to C++: http://felix.sf.net
> 
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