Rewrite rules involving LHS lambda?

[Edward Kmett]

I don't knw of a formal writeup anywhere.

But does that actually mean what you are trying to write?

With the effective placement of "forall" quantifiers on the outside for u
and v I'd assume that x didn't occur in either u or v. Effectively you have
some scope like forall u v. exists x. ...

Under that view, the warnings are accurate, and the rewrite is pretty
purely syntactic.

I don't see how we could write using our current vocabulary that which you
want.

On Sun, Dec 3, 2017 at 4:50 AM, Conal Elliott <conal at conal.net> wrote:

> Is there a written explanation and/or examples of rewrite rules involving
> a LHS lambda? Since rule matching is first-order, I'm wondering how terms
> with lambda are matched on the LHS and substituted into on the RHS. For
> instance, I want to restructure a lambda term as follows:
>
> > foo (\ x -> fmap u v) = bar (\ x -> u) (\ x -> v)
>
> My intent is that the terms `u` and `v` may contain `x` and that whatever
> variable name is actually used in a term being rewritten is preserved so as
> to re-capture its occurrences on the RHS.
>
> When I write this sort of rule, I get warnings about `x` being defined but
> not used.
>
> Thanks,  -- Conal
>
> _______________________________________________
> Glasgow-haskell-users mailing list
> Glasgow-haskell-users at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/glasgow-haskell-users/attachments/20171203/a8d91a47/attachment.html>