[Haskell-cafe] Using multiplate to get free variables from a syntax tree

[Stephen Tetley]

I'm not familiar with Multiplate either, but presumably you can
descend into the decl - collect the bound vars, then descend into the
body expr.

>  Let <$> decl child d <*> expr child e

This seems like a common traversal that Strafunski would handle, and
with Multiplate being a competitor / successor to Strafunski it should
be able to do it too. Naturally you would need a monadic traversal
rather than an applicative one...