17 Feb
2013
17 Feb
'13
10:33 a.m.
Has anyone formulated a reasonable set of laws for MonadReader? The instances for continuation-based monad transformers contradict any intuition about local and ask. E.g. for LogicT:
flip runReader 1 $ observeAllT $ local (const 2) ask [1]
flip runReader 1 $ observeAllT $ local (const 2) mzero <|> ask [2]
I wonder whether there are any real use cases for such instances (and, consequently, whether they should be removed). Roman