I think I see, but if the objects are types, arn't the morphisms functions
on types not values?
Keean.
Ashley Yakeley wrote:
In article <[EMAIL PROTECTED]>,
Keean Schupke <[EMAIL PROTECTED]> wrote:
I am sure monads in Haskell (and other functional languages like ML) are
defined on types not values.
The objects of the category are types. The morphisms on the category are
functions. Two functions are the same if they match each value to the
same value. For the Functor laws and the Monad laws, the values
certainly do matter: if they didn't, they wouldn't correspond to the
category theory notions of functor and monad because the morphisms would
be wrong.
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