[jhc] Substitutions.

[Lemmih]

Hiya,

I've encountered something I don't understand in E.Subst.
The substitution routine is very eager to inline stuff. It inlines all
the simple applications it can find.
Consider the following example:
(\a -> a+a) expensive
The substitution routine will inline that to:
expensive+expensive
Wouldn't it be prudent to generate this instead:
let a = expensive in a + a

Whether to inline it further would be decided later on.

-- 
Cheers,
 Lemmih