Hmm... I just finished my solution when I saw the mapcar one posted by
Evan. Well, here's mine anyway. It is worse because: 1) it's not a
package, 2) it doesn't support aliased variables (i.e. you can't modify
the incoming arrays like you can with map). But, it does use letters
$a, $b, $c, etc. as Bernie requested. Mine operates on the minimum
number of elements, instead of the maximum, in all of the arrays. Perl6
could do this better with variable aliases.
#!/usr/bin/perl
sub mapn(&@) {
my $coderef = shift;
return () if (@_==0);
my $n = @{$_[0]};
my @result;
foreach my $arg (1 .. $#_) {
$n = @{$_[$arg]} if (@{$_[$arg]} < $n);
}
foreach $i (0..$n-1) {
foreach my $arg (0 .. $#_) {
my $letter = chr(ord('a') + $arg);
$$letter = $_[$arg]->[$i];
}
push @result, &$coderef;
}
@result;
}
my @one = qw(foo bar baz fwip);
my @two = qw(spam ham jam flimflam);
my @tri = qw(1 2 3 4);
my @out = mapn {"$c:$a:$b"} \@one, \@two, \@tri;
print "@out\n";
Chris
Bernie Cosell wrote:
> On 29 Oct 2002 at 13:05, Bernie Cosell wrote:
>
>
>>I'm cobbling up a bit of code that'll need to do something akin to 'map' on two
>>lists at the same time. ...
>
>
> Footnote: I realized, that while doing 'mapN' is interesting. what I'm actually
> in the midst of implementing is 'foreach' for multiple lists. The template I
> had in mind was something like:
> forall my ($lotsofvariables) (list of listrefs)
> and then it'd alias the vbls in the lotsofvariables [or en masse if there's an
> array, of course] to each parallel entry from the various lists.
>
> I wonder if there's a pretty/elegant way to do that...
>
> /bernie\
>
