Larry Wall writes:
> On Wed, Jan 21, 2004 at 08:51:33PM -0500, Joe Gottman wrote:
>
> : Great, so
> : $x = foo(), bar();
> : means the same thing as
> : $x = ( foo(), bar() );
>
> No, we haven't changed the relative precedence of assignment and
> comma. I've been tempted to, but I always come back to liking the
> parens for visual psychological purposes.
But that does lead to propagating the myth that parens, rather than
commas, denote lists.
> Plus changing the precedence would break
>
> loop $i = 0, $j = 0; $x[$i,$j]; $i++, $j++ { ... }
I think that matters less -- assigning lists is a much more common
operation that using a C-style C<for> loop, and is also something that's
a common source of errors with beginning Perl 5 programmers. Most of
the C-style C<for> loops I see are unnecessary anyway:
* The majority of them are iterating through array indices (which are
then only used to look up elements in those arrays), something far
more easily achived with a C<foreach> loop and letting Perl take
care of the indices.
* Many of the remainder are still iterating through consecutive
integers, where C<for my $i (1 .. 10)> or whatever would much tidier
than checking the boundary and increasing the iterator manually.
* Even for situations which 'genuinely' need the C-style loop in Perl
5 (such as looping through items in an array but also having the
index number available) many of those in Perl 6 can use C<zip>.
So I think it's odd to optimize for convenience of a construct that has
so little use.
Especially when there are ways of writing that statement without any
commas in it:
loop $i = $j = 0; $x[$i,$j]; do { $i++; $j++ } { ... }
While on the topic of C<loop> and parens, it hadn't occurred to me that
the former could now be written without the latter; I knew that C<for>,
C<if>, and C<while> could be, and now I look at it I can see that
C<loop> can be so-written unambiguously -- but having 'internal',
unbracketed, unquoted, unprotected semicolons scares me a little.
I'd feel more at ease if on seeing something like:
loop $i = $j = 0;
I could be certain that that semicolon denoted the end of that
statement, without my having to know what C<loop> does.
Again, given how infrequently C<loop> is likely to be used, would
imposing such a rule be much of a hardship? So a loop could look
something like:
loop($i = $j = 0; $x[$i,$j]; do { $i++; $j++ }) { ... }
and it's blindingly obvious that the first semicolon couldn't possibly
be the end of the statement.
Smylers
