gistfile1.lhs

If you could say

> ordBy :: Eq a => (a -> a -> Ordering) -> instance Ord a
> ordBy f = instance Ord a where compare = f

and then something like

> sort #(ordBy blabla) xs

then you don't need `sortBy` anymore!

You could even have two instances `Monoid Int`!

> sumInt :: instance Monoid Int
> sumInt = instance Monoid Int where
>     mempty = 0
>     mappend = (+)
> 
> productInt :: instance Monoid Int
> productInt = instance Monoid Int where
>     mempty = 1
>     mappend = (*)
> 
> sum = mconcat #sumInt
> product = mconcat #productInt