HaloO Larry,
you wrote:
Num-to-Int autocoercion is an explicit exception built into the
language. Perl 5 programmars would lynch us if we broke it. But yes,
it's basically cheating.
In your array subscript reply you conceded that flooring
is better behaved than truncation. Which would mean that
-4 === Int(-3.25) should be True. This is important if the
right hand side is an auto-coerced parameter:
sub foo (Int $x)
{
if $x === -4 { say "floored" }
}
foo(-3.25);
sub distance (Int $from, Int $to) { return $to - $from }
say distance(-3.3, 2.3); # should print 6 or perhaps 5.6
The 5.6 return value would somehow maintain the type
prior to the auto-coercion and not violate the unspecified
return value of foo. That is, one needs a sig of :(Int,Int-->Int)
to also force an Int return value. But then that would be
floored to 5. So one way or another you loose precision
when making the Num to Int transition. With auto-coercion
results '-4 but -3.3' and '2 but 2.3' one could calculate a
return value '6 but 5.6' and maintain a maximum of information
while staying type safe.
Hmm, and floor(-0.0) == -1? But this does not carry over the
Num equality -0.0 == +0.0 to Int. So what is more important
sign or magnitude? BTW, does floor return an Int or a Num?
Regards, TSa.
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