On 2008-Dec-3, at 10:18 am, TSa wrote:
Darren Duncan wrote:
Strong typing in Perl means that Perl is conveniently and reliably
keeping track of this user-intended interpretation of the data, so
it is easy for any piece of code to act on it in a reasonable way.
Strong typing lets user code be clean and understandable as it
doesn't have to do a lot of manual book keeping or error checking
that Perl can do for it, such as detecting the error of passing a
character string to a numeric multiplication operator.
First I have a question to the example of the behavior of a string
in a multiplication. Perl 6 automatically attempts a numerification.
But does that result in a failure for 'foo' or does that return 0?
That is, '3' * 3 == 9 is well formed and 'foo' * 3 is malformed,
right?
That's what I would expect. A reasonable default would be for
lossless conversions to happen automatically and lossy ones to throw
an error.
[...Are Enums === Ints?]
This multi is only allowed if A and B are types distinct from Int
which to me implies that enums have a WHAT that is not Int. Opinions?
Using int8 vs Int is presumably a performance issue, but "int8 29" and
"Int 29" *mean* the same thing, so they should be ===. An Enum
doesn't mean the same thing as a plain Int, so it shouldn't.
(As you point out, you can always use something like "Weekday::Sun eq
Star::Sun" or "Weekday::Sun == 0" if you want string or numeric
equality.)
A further question is which operators are automatically generated
for enums. Does
my Int $a = A::One;
$a++;
increment from A::One to A::Two or to the Int 2? What shall happen
when A::Three is incremented? Failure or switch to Int? What happens
with non-continuous enums? My vote would be to not generate any
operators
Since ++ works on strings without making them numbers, I think it
should increment from A::One to A::Two. But if that's ambiguous, we
could drop the ++ and stick with .=succ for non-numeric objects instead.
-David
