inlining higher-order-functions?

[Simon Peyton-Jones]

| My example is complicated, so let me present a simpler analogy.
| Suppose I defined
|
| compose :: (b -> c) -> (a -> b) -> (a -> c)
| compose f g = \x -> f (g x)
|
| I can easily persuade GHC to inline 'compose'.
| But when 'compose' is applied to known arguments, I wish
| f and g to be inlined in the body of 'compose'.
| Is there a pragma that will do the trick?
| (I attempted to put an INLINE pragma in a where clause,
| but GHC was not amused.)

You can put inline pragmas on f and g, thus

        frob = ...
        {-# INLINE frob #-}

        burk = ...
        {-# INLINE burk #-}

        wibble = compose from burk

Now compose will be inlined (assuming it too has an INLINE pragma), and then frob, burk.

Simon