Can Class do this?

I have a problem as follows - type CF = Char -> Float type IF = Integer -> Float type CIF = (Char,Integer) -> Float There be two functions: fun :: CF fun = fromInt.ord sun :: IF sun = fromInteger I want the followings to be valid. x :: IF x = sun \+ sun y :: IF y = sun \+ sun \+ sun -- when only sun is there, type should be IF a :: CF a = fun \+ fun b :: CF b = fun \+ fun \+ fun -- when only fun is there, type should be IF p :: CIF p = sun \+ fun q :: CIF q = sun \+ fun \+ sun - -when sun and fun are mixed type should be CIF I guess this can be done using classes, but I have not been successful after trying many variations. Any help is very much appreciated. Thanks, Saswat