10 Oct
2011
10 Oct
'11
8:08 a.m.
On Oct 9, 2011 11:17 PM, "David Barbour"
If you really want the input type to be part of the Filter type definition, you'll need to use arrows instead of monads.
I wouldn't say that. You just need an extra type parameter. That doesn't mean it can't be a monad. In fact, wrapping ReaderT around the existing representation gives us exactly the monad we probably want. That said, I think it is likely to be more useful in this context either as it is or as an arrow. I just want to point out that it can still be a monad even if it is an arrow. - Jake