[Haskell-cafe] StateT and ContT

Ross Paterson R.Paterson at city.ac.uk
Tue Jan 20 18:02:43 UTC 2015

On Wed, Jan 21, 2015 at 12:09:13AM +1100, Ivan Lazar Miljenovic wrote:
> This is what I thought: I just wanted to make sure that I wasn't
> missing something (especially since there's no real documentation that
> I could find as to _how_ liftCallCC' fails to satisfy the laws of a
> monad transformer).

Any lifting of callCC should satisfy

	lift (f k) = f' (lift . k) => lift (callCC f) = liftCallCC callCC f'

and liftCallCC' doesn't.

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