Not sure if this is p6l or p6c... Fallback to the latter. :) In this line:
[Dog ::T $ ($x) where 1, *$, [EMAIL PROTECTED] := moose();
the left hand side is probably not a valid Perl 6 expression, yet
according to the current spec, it needs to be parsed implicitly as if a
:() is around it.
How does this work in practice? Is an infix macro allowed to change the
"is parsed" of its LHS? Should that trigger a reparse, or do we use
(potentially costly) prescanning?
A way out of this may be requiring :() on the LHS of :=, and treat it as
an infix macro that only changes how the RHS is parsed (which would be
trivial). Or, for symmetry, make := ordinary infix, and require both
side to be :() and \() respectively.
I agree that
($x, $y) := ($y, $x)
is clean (and featured in various places). However, as long as there
are some Signature forms that isn't valid expression form, or would
triggered parse-time expression-form macros that wouldn't trigger in
Signature forms, I can't figure out how it would work.
The infix:<=> has no such problem because all valid lvalue expressions
are also valid rvalue expressions in Perl 6.
Thanks,
Audrey
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