I wrote:
> Damian explains:
> > Trey asked:
> >
> > > To take the E6 example of currying &part:
> > >
> > > &List::Part::part.assuming(labels => <<sheep goats>>)
> > >
> > > One had to curry in C<labels> to be the same as it was defined in C<&part>
> > > originally, i.e. C<< <<sheep goats>> >>.
> > >
> > > What if one wanted to curry in whatever the default is, i.e., assuming
> > > "nothing" (different from "assuming nothing"), so that if List::Part::part
> > > changed its default for C<labels> to C<< <<oves caperes>> >>, the client
> > > code would pick that up?
> >
> > If you're assuming "nothing", don't use C<.assuming> (since you aren't ;-)
> > Just write:
> >
> > sub my_part(Selector $s, [EMAIL PROTECTED]) { part $s <== *data }
> >
> > and let C<&part> do the assuming for you.
>
> Gee, that's about as helpful as saying to do &baz.assuming(foo => 'bar'):
>
> sub my_baz([EMAIL PROTECTED]) {
> baz foo => 'bar' <== [EMAIL PROTECTED]
> }
>
> Wasn't the whole idea of assuming to make it easy to curry without
> knowing the entire signature, and being tolerant to changes? I see a
> simple solution:
>
> our &my_part := &part.assuming('labels');
>
> Or, maybe if we're caught up on readability (and error checking):
>
> our &my_part := &part.assuming(none 'labels');
Here's a wacky idea. We have C<undef> for for undefined, and
C<defined> to check it. We have C<exists> to check existance, so,
(hold your breath) C<nonex>.
A synonym of:
delete %h{foo};
would be
%h{foo} = nonex;
To assume that a value wasn't provided:
our &my_part := &part.assuming(labels => nonex);
And to declaratively copy a hash but delete a key:
{
%other,
baz => nonex,
}
> Luke
>
> > Damian
