[nem-en] Parentheses

[Maurizio Colucci]

On Wednesday 08 September 2004 16:47, Pawel W. Olszta wrote:
> Hello Maurizio,
>
> > With the ongoing update to the type inference (I read the Monologue :-)),
> > the only thing that is holding me back from using Nemerle (instead of
> > ocaml) is the heavy notation with too many parentheses, especially for
> > lambdas:
> >
> > Nemerle:
> >
> > List.Map ([B()], fun (x) { x.foo });
> >
> > Ocaml:
> >
> > List.map [new B]  (fun x -> x#foo)
>
> I've made a little experiment and you'll probably be able to write:
>
>     List.Exists ([1, 2, 3, 4, 5], lambda x -> x == 3)
>
> The (very simple) `lambda' (as the `fun' keyword is already taken and
> our parser can't differentiate between the two constructions
> automatically yet) macro should make it to tonight's snapshot unless I
> fail to convince Kamil, who's opposing to pollute the language with
> such syntactic sugar.

Very nice :-). What is the syntax for functions that take more than one 
argument? 


  lambda x y -> x+y 

?

>
> > I understand the syntax is meant to be similar to C#, but this should be
> > taken into consideration. Does nobody feel this as a problem?
>
> Personally, I am a natural born LISP person :)
>
> > PS: Even better would be:
> >
> > List.Map [B()]  (fun x -> x.foo);
> >
> > but I understand this would make too much of a change.
>
> This looks like partial application to me and we're not supporting that.

No, no, it's not a partial application: Map requires two arguments and two are 
given. What gave you that impression? 
It was just an attempt to write a ocaml/clean/haskell-like syntax (see the 
ocaml example above). With this notation, what in nemerle you write

f(x, g(x, y, h(z)))

becomes

f x (g x y (h z))

See how much nicer it is to the eye? ;-)

> > PPS: And what about removing () from B()?
>
> You need the () to differentate the construction of an instance of
> type B from referencing the type B. Moreover the `B ()' notation is
> consistent with the rest of the language.

Right. 

> And I'd hate to see `()' being replaced by the `new' keyword, it seems
> redundant to me as you have to write the parens anyway if the called
> constructor has any parameters ;]

Unless you adopt the above notation, where instead of 

  f(a, g(x, y));

you write

  f a (g x y);

Are there any reasons not to? (other than similarity to C#)

> Thanks to your feedback, I have a feeling that this topic is going to
> attract a lot of attention :)
>
> Pawel Olszta

:-)
keep up the good work.
-- 
Maurizio Colucci
http://logicaldesktop.sourceforge.net