gistfile1.txt

Alternatively (and equivalently), local implicit module bindings for Ord and Ord_int_rev make it possible
to override the behaviour at ints while using the automatic resolution behaviour to locate and use
the Ord_pair functor:

```
let sort_both_ways ( items : ( int * int ) list ) =
let ord =
let implicit module Ord = Ord_int in
sort items
in
let rev =
let implicit module Ord = Ord_int_rev in
sort items
in
ord , rev
```

In Haskell, which lacks both local instances and a way of explicitly instantiating type class dictionary
arguments, neither option is available, and programmers are advised to define library functions in pairs,
with one function (such as sort) that uses type classes to instantiate arguments automatically, and one
function (such as sortBy) that accepts a regular argument in place of a dictionary:
```
sort :: Ord a = > [ a ] -> [ a ]
sortBy :: ( a -> a -> Ordering ) -> [ a ] -> [ a ]
```