On Fri, May 02, 2008 at 11:34:33AM +0200, TSa wrote:
> My idea is that foo:( Foo &f ) should mean the same as
> foo:( Foo $x ), that is the variables have to contain a
> value that does Foo.
No, I think &f should be treated more like @f and %f as a composite
object with a normal return type for the standard usage of the object.
Just as @ already implies "Array of" and % already implies "Hash of",
so too & already implies "Function of".
> Note that this implies that
>
> sub mysub {...}
>
> occupies two slots in the surrounding namespace &mysub and
> ::mysub. The latter is a type that can be used as
>
> sub mysubuser ( mysub &f ) {...}
>
> sub yoursub does mysub {...}
>
> mysubuser( &yoursub ); # OK
>
> sub blahh (Int $x) does mysub {...} # composition error
I don't think most people want to think of functions as types--it just
clutters up the type namespace. They can already say:
sub mysubuser ( &f where &mysub.sig ) {...}
or some such to do explicit smartmatching against the &f object.
Alternately if they really want the type they can say
subset mysub of Code where &mysub.sig;
sub mysubuser ( &f where mysub ) {...} # note &
sub mysubuser ( mysub $f ) {...} # note $
Larry
