Consider this example:

applyKTimes :: Integral i => i -> (a -> a) -> a -> a
applyKTimes 0 _ x = x
applyKTimes k f x = applyKTimes (k-1) f (f x)

applyThrice :: (a -> a) -> a -> a
applyThrice = applyKTimes 3

The 3 in applyThrice is defaulted by GHC to an Integer as shown when compiling with -Wall:

Warning: Defaulting the following constraint(s) to type 'Integer'
         'Integral t'
           arising from a use of 'applyKTimes'

So I guess that Integer is the default Integral a => a.

• Is there a way to define "default types" for other constraints too?
• Is using default types bad practice? (it does complain when using -Wall..)