Henry Baragar Henry.Baragar-at-instantiated.ca |Perl 6| wrote:
I think that in your "Example 1", that you may be making too making too much
of a distinction between "$a" and "@a". That is:
sub f2(@y) {...}
has exactly the same signature as
sub f2($x is Array) {...}
In other words, they both take a single argument that must be of type Array.
Hence, @y and $x work the same "beneath the surface" and there is no extra
level of indirection.
But... $x has an Item container, and @y doesn't !
Now that we are viewing parameters as providing constraints rather than
contexts, we get a different view on your "Example 2". I made your example
more concrete and ran it through rakudo, yielding:
> sub f1 ($x) {say $x.WHAT}; f1(Nil);
Nil()
> sub f2 (@y) {say @y.WHAT; say +...@y}; f2(Nil);
Array()
1
>
Why doesn't +...@y produce 0, not 1? It's an empty list.
And if the argument types are viewed as constraints only, denoting
whether the call is acceptable but not changing anything about it, and
f2 is written as way above, the two functions would produce the same
output. Clearly they're not.
See, no problems with f2().
Good. Thanks.
