15 Nov
2012
15 Nov
'12
7:45 a.m.
On Wed, 14 Nov 2012, Tyson Whitehead wrote:
That is, is it also sensibly a non-Pointed Monad?
TMap implements Applicative and Monad instances corresponding to the Reader monad. That is, join m ! k == m!k!k. This would not work with a
On Wed, Nov 14, 2012 at 5:37 PM, Henning Thielemann < lemming@henning-thielemann.de> wrote: plain Data.Map, since (m!k!k) may not exist. If (m ! k) exists but (m ! k ! k) does not, that just means (join m ! k) does not exist. join = Map.mapMaybeWithKey Map.lookup This is the semantics we would get with ReaderT k Maybe and, if it existed, TMapT k Maybe. - Jake