Haskell function seeking further explanation -

i've been trying create haskell function gets largest odd integer in list. sounds easy, , sure thought looks i'm stuck! here code, far returns largest number in list including both odd , numbers:

maximum :: (ord a) => [a] ->   maximum [x] = x   maximum (x:xs) = max x (maximum xs) 

thank in advance help!

first of - if have elements in list have problem, function not total (i.e. produces error) - best modify type of result account possibility:

also others have mentioned - odd requires constraint integral instead of ord.

maximodd :: integral => [a] -> maybe maximodd xs = case filter odd xs' of                 []  -> nothing                 xs' -> (maximum xs') 

the function filter odd removes non-odd elements (i.e. numbers) - pattern match on result account failure.

if want work original function code gets lot more tricky:

maximum :: integral => [a] -> maximum [x] = x maximum (x:xs) = let y = maximum xs                  in if x >= y && odd x                       x                       else if x < y && odd y                              y                              else ?? 

hmm - don't think can make work - maybe helper function.

maximum :: integral => [a] -> maybe maximum xs = maximum' nothing xs   maximum' nothing (x:xs) = if odd x                                     maximum' (just x) xs                                     else maximum' nothing xs         maximum' (just y) (x:xs) = if odd x                                      maximum' (just $ max x y) xs                                      else maximum' (just y) xs         maximum' x _ = x 

which more complicated - , haskell not known being complicated ;)