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Postings from September 2005
Imagine you're writing an implementation of the unix "uniq" function:
my $prev;
for grep {defined} @in -> $x {
print $x unless defined $prev && $x eq $prev;
$prev = $x;
}
This feels clumsy. $prev seems to get in the way of what I'm trying to
say. Could we imbue optional binding with the semantics of not being
consumed?
for grep {defined} @in -> $item, ?$next {
print $item unless defined $next && $item eq $next;
}
The same behavior, but without the variable outside the loop scope.
It would also be good not to overload the meaning of $?next to also tell
us if we're at the end of the loop. In addition to FIRST{} and LAST{}
blocks, could we have some implicit lexicals:
for @in -> $item, ?$next {
print $item if $?LAST || $item ne $next
}
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