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RE: [Caml-list] Future of labels
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Date: 2001-04-01 (20:59)
From: kahl@h...
Subject: Re: [Caml-list] Future of labels
Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp> replied to
  "Manuel Fahndrich" <maf@microsoft.com>:

> > 1) The standard library requires ~f: labels on many function arguments.
> > That seems silly. I basically had to add ~f: to many places where it did
> > not add disambiguation (f is not a very explicit name). I can see that
> > for partial applications that might be useful, but still I found this a
> > bit annoying.
> Not really for partial application (you rarely want to apply to a list
> before the function), but rather for layout. Mostly a question of
> taste, but if you like it really changes the way you use functionals.
> Anyway, if we remove labels from the standard library, this would
> solve the problem.

I am a long-time label user (having started when OCaml still was
Caml Special Light) and I have therefore gone through quite a few
relabellings of the standard library.
They never really hurt me (with a 50 module 30000 line project) ---
only when labels went away, it meant trouble.
(To make it clear: I ONLY use label mode and do not intend to switch.)

Jacques' words seem to indicate that there seems to be a
complete unlabelling of the standard library in the works ---
I must confess that I do not like that at all.
(Is my interpretation right? I got the impression that
 this was the only change intended for label mode.)
Especially for the ``f'' label!
(This was ``fun'' before the OCaml/OLabl merger
 and had to be changed to accommodate the new rule that
 keywords were not allowed as labels anymore ---
 I'd rather have the keyword ``fun'' replaced by Haskell's ``\'',
 or by a real lambda in a suitable character set!)

My point with the ``f'' label is that I need it almost always:
For List.map, List.fold_right and friends I usually have
only simple list arguments, but complex functions,
and do not see the point why I should
let-define that function beforehand.
So I think it is most readable to write the following:

  let list3 = List.map list2
               ~f:(fun x -> .....
                            ... x ...
                            ..........) in

If the ``f'' label goes away,
then I need a labelled wrapper around the standard library.
If none is provided, I have to write it myself,
but I would much prefer to have a standard labelling of the standard library,
since this also provides the label-using community with useful conventions and

And I do find the labels in the standard library useful with OCamlBrowser --
I use that much more than my copy of the html-version of the OCaml manual!


Wolfram Kahl

And if the ``f'' label was to go away 
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