Larry Wall wrote:
On Thu, Mar 19, 2009 at 02:18:35PM -0700, Darren Duncan wrote:
Yes, --> is the "of" type, not the "as" type, as S02 I think says.


Good to know.

Second, since the "sub NAME (PARAMS --> RETTYPE) {...}" form looks nice visually, I would like to request a variant of that form, that flips the arrow:

  sub NAME (RETTYPE <-- PARAMS) {...}

Well, yes, that would be pretty, but the big problem with it is that
it's terribly ambiguous, given that the other-ended form can also
start with a type.  (I can think of at least five mechanisms to force
it to work, but they're all pretty ugly when we're trying to maintain
a predictive parser outside of opererator precedence expressions,
which this isn't one of.)  It's also getting just a little dicey to
provide a *fourth* way to do something when we already have three.

Maybe the problem is a technicality with the parser because ...

I'm guessing that the problem is that until you see the <-- then what you've read so far on its left is ambiguous as to whether it is a result type or a parameter. I can understand that but I don't know if its a big problem.

AFAIK the token <-- isn't used anywhere yet in Perl 6 and so its presence inside a parameterized list would be unambiguous once you've read up to it.

Anyway, while I would appreciate if <-- worked, if it doesn't then I can live with one of the existing alternatives ('of' being my current preference). This is a "nice to have" but not something I would push as hard yet as some other issues.

Thank you. -- Darren Duncan

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