[racket-dev] Release Announcement for v5.0.1 -- final version

From: Michael Sperber (sperber at deinprogramm.de)
Date: Mon Aug 2 03:49:15 EDT 2010

Eli Barzilay <eli at barzilay.org> writes:

> I don't know of any plan for signatures, but if it would be bad to
> advertise it if it's not included...  Jay/Ryan--??

Signatures are already in there (look in the log in collects/lang) -
they're just not documented yet.  They already give you this, for

(define-struct foo (a b))
(define-struct bar (c d))
(define foo-or-bar
  (signature (mixed foo bar)))

At the very least, `define-datatype' should also define a signature.

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla

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