Various improvements and fixes.
- Fixed
ifte
and made thenonDetEffTests
better. - Fixed
runC
for theYield
effect. - Added a
runM
handler for running an arbitrary monad (if it's the only effect left to handle). - Added a
modify
function for the State effect. - Removed the
ProxyState
type wasn't necessary in favor ofData.Proxy
. - Made the
Writer
effect work with arbitrary monoids instead of just lists.