[Haskell-cafe] Origins of '$'

Nathan Bloomfield nbloomf at gmail.com
Mon Dec 8 16:59:35 EST 2008

>> In set theory, and sometimes in category theory, A^B is just another
> notation for Hom(B, A), and the latter might be given the alternate notation
> B -> A. And th reason is that for finite sets, computing cardinalities
> result in the usual power function of natural numbers - same as Church,
> then.
>  Hans

Slightly off topic, but the A^B notation for hom-sets also makes the natural
isomorphism we call currying expressable as A^(BxC) = (A^B)^C.

Nathan Bloomfield
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