Re^5: A "but" operator.

in reply to Re^4: A "but" operator.
in thread A "but" operator.

This is where predicate logic doesn't work as well as set theory. "A but B" is actually more akin to "A minus B", where A and B are both sets. Or, in Perl,

my @A = ( ... );
my @B = ( ... );

my %B = map { $_ => !!1 } @B;

# "A but B"
grep { !$B{$_} } @A;
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Which is very close to the mixin concept that Perl6 will apply to the term "but".

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

I shouldn't have to say this, but any code, unless otherwise stated, is untested

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