* Sean Leather [2011-09-04 12:48:38+0200]

> On Sun, Sep 4, 2011 at 12:31, Roman Cheplyaka wrote:
>
> > I'm looking for an example of idiomatic usage of the fixpoint library[1].
> >
> > [1]: http://hackage.haskell.org/package/fixpoint-0.1.1
>
>
> I'm not sure if this counts for idiomatic usage, but you can check out
> our approach to incrementalization.
>
> http://people.cs.uu.nl/andres/Incrementalization/

Yeah, it has more or less the same problems as my code above.

You essentially defined your tree twice (Tree and F (Tree)).
For such a simple type it's fine, but if it was an AST with a few
dozens of constructors, such approach would be unacceptable.

True. Technically, one doesn't need Expr or Tree, right? But if you prefer to define your datatype that way, that's usually where I turn to code generation, possibly using Template Haskell, Data.Derive, or something else.

Sean