New recently in Redex: - Redex's where patterns now accept the full pattern language of Redex (this is another source of ambiguity, of course, so it may also give rise to multiple ways that a rule may fire).
- Added define-relation. This represents a relation as a function to booleans. define-relation definitions looks a lot like define-metafunction definitions, but it relaxes the constraint that there is only one case that applies and instead if any case produces #t, the relation is considered to hold. Also, there can be multiple expressions in the body of a single case; those must all hold for the case to hold. The intention is that this matches a little bit better relations that are written down in sequent style. (But do keep in mind that there are no fundamental changes here -- Redex cannot do any prolog-like search or anything like that). - The restriction that a metafunction definition has a single way for a pattern to match has been slightly relaxed; specifically if all of the ways that a pattern can decompose produce the same results, then no error is signalled. For example, that allows this definition of set minus: (define-language empty-language) (define-metafunction empty-language [(minus (any_1 ... any_2 any_3 ...) (any_2 any_4 ...)) (minus (any_1 ... any_3 ...) (any_2 any_4 ...))] [(minus (any_1 ...) (any_2 any_3 ...)) (minus (any_1 ...) (any_3 ...))] [(minus (any_1 ...) ()) (any_1 ...)]) whereas in the previous versions, this call: (term (minus (1 1 1) (1))) would have signalled an error. Robby _________________________________________________ For list-related administrative tasks: http://list.cs.brown.edu/mailman/listinfo/plt-dev
