Carl Mäsak wrote:
Paul (>):
I can't find anything in the existing synopses about Blobs.
Probably looking in the wrong place, sorry.
<http://perlcabal.org/syn/S02.html#line_912>
Re-reading that, a slightly tangent (though still on topic, I hope)
thought come to mind. The definition of the Mapping immutable type:
Mapping Set of Pairs with no duplicate keys
The question is, what to do when a Mapping is created from a
source that contains pairs with duplicate keys? The Perl5 answer is
simply to silently drop all but the last in the list ... but I can think
of many other answers: sometimes you might want an error; other times
you might want to create a list/set/bag from the values of the duplicate
keys; other times a junction might be appropriate. One theme of P6 is to
not lose information unnecessarily -- which is what P5 does here.
The option of creating a list of the values is interesting because, in
scalar context, a list returns the value of its last item -- which is
the existing P5 semantics but without losing information until the value
is used as a scalar. And lists can be used to construct all the other
interesting cases.
Will there be a syntax for choosing the strategy for reducing a list of
pairs that contains duplicate keys to a "Mapping"?
