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If OCaml were a car
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| Date: | -- (:) |
| From: | Jon Harrop <jon@f...> |
| Subject: | Re: [Caml-list] If OCaml were a car |
I'm quite surprised to hear so many non-specific complaints. There are, as
always, some tweaks I'd like to make...
On Sunday 19 August 2007 22:45:41 skaller wrote:
> Ocaml has lots of syntactic issues. It has too many operators,
> so that it is hard to remember their 'precedence'. Some are
> very un-natural, for example:
>
> if e then e1 else e2
>
> The thing is that 'else' has a different 'precedence' than 'then'.
> So you can write:
>
> if e then e1 else a; b; c
>
> and a,b,c are all executed if the condition is false,
I do not believe this is true. The "b" and "c" are executed in both cases
because the above is parsed as:
(if e then e1 else a); b; c
which is syntactically uniform:
# (<:expr< (if true then a else a);b;c >>) =
(<:expr< if true then a else a;b;c >>);;
- : bool = true
Perhaps you were thinking of this:
if p then t else
let () = () in
f1;
f2;
f3
because "let" binds more tightly.
> Furthermore, because of the decision that procedures
> return unit, you can write:
>
> if e then p;
>
> without the else, but only if p has type unit: the syntax is so
> confused it doesn't know if it is functional/expression based
> (in which case the else expression should be mandatory)
> or procedural (in which case procedure calls should return void
> to prevent the call being used as an argument to an application).
Why should the return value (of unit) not be used as the argument to an
application?
> Well it is NOT clear that all these alternatives are actually
> a good idea, just as it is NOT clear that excess use of camlp4 is
> a good idea. In my experience, using the language's raw syntax,
> even if it has warts, is more or less mandatory if you want
> other people to be able to read your code.
Yes.
> Can Ocaml syntax be improved? Yes, but not much. Felix has:
>
> print$ "Hello" + " World";
>
> which is stolen from Haskell and gets used a lot. Even if I can
> implement that with camplp4 I wouldn't. I'd like to see $ in
> the standard language: then I'd use it.
You might prefer the F# operators |>, << and >>.
For syntactic changes, my personal vote goes to some very useful syntactic
extensions rather than any replacements, and ones that don't (in practice)
break backward compatibility.
Boolean expressions could permit:
a < b <= c
Asymmetric whitespace allows a new unary minus operator with higher
precedence:
a - b -> Sub(a, b)
a -b -> Apply(a, -b)
a-b -> Sub(a, b)
That's pretty much all I can think of. The rest is fine by me. I'd much rather
see effort go into an IDE rather than tweaking the syntax and breaking
backward compatibility.
--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists/?e