Rod Adams wrote:
And then internally dispatch on what is defined and undefined.
Why all that burden if Perl 6 is getting a strong type system,
that can do the sub selection and compile in dynamic dispatch if
needed?
I imagine:
multi sub cos( Num +$angle ) returns Num where { -1.0 <= $_ <= 1.0 }
class Radians is Num
{
}
class Degrees is Num
{
postfix:<°> ( Num $x ) { return $x * PI / 180 }
multi sub cos( Degrees +$angle ) returns Num where { -1.0 <= $_ <= 1.0 }
{
return cos( $angle * PI / 180 );
}
}
Note that cos(30°) calls &cos<Num> while &cos<Degrees> is used for
cases like:
Degrees $angle = 30.0;
if cos $angle > 2.0 { print "HaloO typechecker!" }
And I still wonder if the ones without '°' on their keyboard could
directly call 'cos<Degrees> $angle'.
Regards,
--
TSa (Thomas Sandlaß)
