Jordan Cooper wrote:
Secondly, as to why I wanted to use a monad here, importantFunction (which is called playerTurn in the real program) would contain a series of functions that would modify Cards and Players, not just one each as in my initial example. Thus it seems like I'd have to end up with let foo... let foo'... etc. which, from my reading in RWH, seems to be an acceptable use for a State monad.
While your use of the state monad may well be sensible, keep in mind that many cases of "threading state" are covered by ordinary functional programming idioms, like function composition process = take 3 . sort . map length . filter (not . null) . lines and accumulating parameters average xs = foldl' step (0,0) xs where step (!s,!n) x = (s+x, n+1) reverse xs = go xs where go ys [] = ys go ys (x:xs) = go (x:ys) xs The functions in Data.Map are a good example as well: most of them "change" the map, but a state monad would be overkill for that. The state monad is mainly beneficial when you otherwise would have many functions of type :: s -> (a,s) with ugly plumbing like let (a,s') = foo s; (b,s'') = foo s' in .. Regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com