Re: lambda, ->, haskell, and so on

On Sun, May 11, 2008 at 9:49 AM, Nobuyoshi Nakada <[e-mail]>
wrote:

> Hi,
>
> At Sun, 11 May 2008 15:14:54 +0900,
> Evan Phoenix wrote in [ruby-core:16705]:
> > Not to throw the whole thread into a tizzy again, but why again is:
> >
> >   ->(a,b) { }   # stabby proc
> >
> > better than
> >
> >    def(a,b) { } # anonymous def
>
> It would conflict with singleton method definitions.
>
> --
> Nobu Nakada
>
>
I've never seen the ()'s used for the "singleton".  i.e.

def (a+b).foo
...
end

Is it necessary to preserve compatibility to do this since nobody really
uses it?  You could still do the above with:

c = a+b
def c.foo
...
end

My personal preference would be to not introduce some brand new
block/lambda/proc/def form.  I think there is already enough confusion
around the topic.  Instead, just extend block arguments to allow for
defaults and its own block argument.  i.e.

... { |a, b=1, c=(d|e), &f| ... }

To handle the ambiguity between "|" in the default value vs. the argument
list terminator, I think the only thing that you'd need to do is to restrict
the default value to be "primary" instead of "arg_value".  For a "def", an
optional argument in parse.y is:

f_opt           : tIDENTIFIER '=' arg_value

For a block, it would just be:

block_f_opt : tIDENTIFIER '=' primary

and you'd change block_params to allow block_f_opt like f_args allows for
f_opt.

Any downside with this?

Eric