Yitzchak Gale wrote:
I wrote:
...it was recently claimed on this list that tuples
are not products in that category.
I've not been convinced yet.
I'm going to try convince you :) The crucial problem of Haskell's
product is that (_|_,_|_) ≠ _|_ but that the two projections
fst :: (A,B)
Jonathan Cast jonathanccast at fastmail.fm writes:
Extensionality is a key part of the definition of all of these
constructions. The categorical rules are designed to require, in
concrete categories, that the range of the two injections into a
coproduct form a partition of the
On 6 Jan 2008, at 12:27 PM, Dominic Steinitz wrote:
Jonathan Cast jonathanccast at fastmail.fm writes:
Extensionality is a key part of the definition of all of these
constructions. The categorical rules are designed to require, in
concrete categories, that the range of the two injections
