Deborah Ariel Pickett:
# [no longer sent to perl6-internals because it's not relevant there]
#
# I see a problem . . whether the problem's with me or the
# grammar, that's for you people to decide.
#
# Do I read this part of the grammar correctly?
#
# > sv_literal: /(?:\d+(?:\.\d+)?|\.\d+)(?:[Ee]-?\d+)?/
# > | '{' <commit> hv_seq '}' <----
# > | '[' <commit> av_seq(?) ']'
# > | <perl_quotelike>
# >
# > hv_seq: <leftop: pair ',' pair> /,?/
# >
# > term: '<' <commit> expr(?) '>'
# > | subscriptable <commit> subscript(s?)
# > | /$CONTEXT/o <commit> term
# > | sv_literal <----
# > | class
# > | closure <----
#
# A "term" can be either a scalar literal ("sv_literal") (which
# might be a hash reference literal), or a closure (which might
# be a block).
#
# Both of those could be written "{ stuff }", for various
# values of stuff, but it looks like the current disambiguation
# rule is "if it's nothing but a sequence of "pair"s, then it's
# a hash ref, otherwise it's a closure.
#
# My perl5 sensibilities tell me that that's likely to cause a
# problem when I want to do something like this:
#
# $hashref = { function_returning_hash() };
#
# because I won't get the function's return values put into a
# hash, because the stuff inside the { ... } isn't a list of
# pairs. Instead I'll get a (reference to) a closure, not at
# all the same thing.
#
# Of course, in perl5, the requirement that "sub" prefix any
# closure-as-a-term nicely disambiguates that, but I understand
# that this is being phased out for perl6 (the grammar backs that up).
#
# How does perl6 distinguish between:
# $hashref = { function_returning_hash() }; # call sub,
# get hash ref
# and
# $subref = { function_returning_hash() }; # make
# closure, don't call sub yet
# ?
When Perl can't disambiguate, you have to do it instead:
$hashref = hash { function_returning_hash() };
$subref = sub { function_returning_hash() };
Of course, there may be other ways for Perl to disambiguate--this one
comes to mind:
my HASH $hashref;
my CODE $subref;
As for the above grammar, I suspect that the <commit> is misplaced. It
should probably be allowed to fall through to the closure.
(Alternatively, always parse it as a closure and afterwards run through
the parse tree, checking all the closures and converting those that only
contain pairs.)
# (I hope the answer isn't "white space" . . )
#
#
# [Hi, I'm new around here, so I'll give you the three-line
# introduction. I teach Perl at Monash Uni, my office is in the
# same corridor as Damian's, and I like cats, chocolate, and
# curry. (Not all at once.) ]
Well, any friend of Damian's... :^)
--Brent Dax <[EMAIL PROTECTED]>
@roles=map {"Parrot $_"} qw(embedding regexen Configure)
He who fights and runs away wasted valuable running time with the
fighting.
