[plt-scheme] is-a? for unit signatures

At Mon, 18 Apr 2005 10:31:06 -0400, Dave Herman wrote:
> With classes and interfaces I can build a predicate to test for 
> interface implementation using is-a?. Is there an equivalent way to test 
> a unit to see if it exports a given signature?
> 
> It seems like you might be able to hack this together with 
> verify-linkage-signature-match, but that procedure has me crying uncle..

I think you want just `verify-signature-match', which is simpler. Use
`signature->symbols' to convert (at compile time) a signature name into
a suitable input, and use `signed-unit-exports' to get (at run time)
the export part of a signed unit.

Matthew