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The only thing I can think of that's wrong with Haskell's functors is that they're more specifically endofunctors, or am I missing something else?
by bstamour 12y ago
The only thing I can think of that's wrong with Haskell's functors is that they're more specifically endofunctors, or am I missing something else?
- jberryman 12y agoAnd Hask is arguably not a proper category
- bstamour 12y agoCan you expand on this? I'm genuinely curious.
- T-R 12y agoMy understanding is that it's not a proper category due to the presence of Bottom - https://wiki.haskell.org/Bottom https://wiki.haskell.org/Bottom > Bottom is a member of any type, even the trivial type () [...] If it were not, the compiler could solve the halting problem and statically determine whether any computation terminated You can imagine function composition and identity don't work too well on things that never complete.
- bstamour 12y agoAh yes, you're right. I always forget about bottom.