Annotating Expressions

[ajb at spamcop.net]

G'day all.

Quoting John Meacham <john at repetae.net>:

> Imagine I have a data structure like so:
>
> data E = EAp E E | ELam Int E | ELetRec [(Int,E)] E | EVar Int
>
> now, I want to annotate every occurence of E with some pass specific
> information, such as free variables or levels for lambda lifting.

        http://haskell.org/hawiki/DecoratingStructures
        http://haskell.org/hawiki/IndirectComposite

Cheers,
Andrew Bromage