[plt-scheme] prop:equal+hash for scheme/class ?

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Sun Dec 28 10:07:10 EST 2008

At Sat, 27 Dec 2008 21:16:27 -0600, Matthew Flatt wrote:
> At Sat, 27 Dec 2008 18:13:58 -0500, Felix Klock's PLT scheme proxy wrote:
> > Is there a prop:equal+hash for the scheme/class collection?
> Not currently.
> > Or perhaps instead of a property, there are a set of methods I am  
> > supposed to override?  (Much like how in Java one is supposed to make  
> > sure that the hashCode() and equals(..) methods must be kept in  
> > sync.)  But if that is the case, the methods are not documented as far  
> > as I can tell.
> > 
> > The documentation for object% says that it "has no methods  
> > fields" (sic) which leads me to think that PLT did not follow Java's  
> > lead (that's good!) and so something more like prop:equal+hash (which  
> > feels more like multi-method dispatch) is what belongs here.
> It would be easy to add an interface for `prop:equal+hash' along the
> same lines as the `printable<%>' interface for `prop:custom-write'. I'm
> open to other suggestions.

I've added `equal<%>' --- and also `interface*', so that other
properties can be mapped to interfaces without building them into

The `equal<%>' interface is implemented with `interface*' and doesn't
need to be built in, but it seems useful enough to include in


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