Proposal: Add Compositor class as superclass of Arrow

Philippa Cowderoy flippa at
Sun Oct 21 15:30:31 EDT 2007

On Sun, 21 Oct 2007, Twan van Laarhoven wrote:

> Ashley Yakeley wrote:
> > 3. There might be another useful class that's a subclass of Category and
> > a superclass of Arrow, that essentially includes first but not arr. If
> > someone wants to name it and define it, we can put it in the class
> > hierarchy.
> My proposal would be the following. The important things are that:
>  1. It incorporates Conal's deep arrow,
>  2. as well as everything that is needed for functional references/lenses
> and bijective/invertible functions.
> I have chosen to reuse prelude names where possible.

Looks good to me. CategoryPair is what I had in mind.

flippa at

"I think you mean Philippa. I believe Phillipa is the one from an
alternate universe, who has a beard and programs in BASIC, using only
gotos for control flow." -- Anton van Straaten on Lambda the Ultimate

More information about the Libraries mailing list