At Fri, 2 Aug 2013 18:32:38 -0400, Asumu Takikawa wrote: > I'm currently trying to implement contracts for synchronizable events. > During that, I've discovered that there seems to be an undocumented > restriction that `chaperone-evt` can only chaperone an event that is not > a handle event. Here's an example: > > -> (sync (chaperone-evt (handle-evt always-evt identity) > (lambda (e) (values e identity)))) > ; wrap-evt: contract violation > ; expected: (and/c evt? (not/c handle-evt?)) > ; given: #<evt> > ; [,bt for context]
The restriction (which should have been documented) is there the same reason as for `wrap-evt', since the procedure in place of `identity' above gets to adjust the result of the event --- and so handling can't be in tail position with respect to `sync'. But I'm ready to throw out the `(not/c handle-evt?)' restrictions everywhere. _________________________ Racket Developers list: http://lists.racket-lang.org/dev
