Sorry-- this was already unchangable 5 years ago, nevermind today. Robby
On Tue, May 1, 2012 at 6:56 PM, Jon Rafkind <rafk...@cs.utah.edu> wrote: > Just in case it was unclear I was hoping people would explicitly adorn > pattern variables if they want to match the same term. > > (simple integer_1 integer_1) > > But if (simple integer integer) to match the same term twice is a heavily > used form then so be it.. > > On 05/01/2012 05:52 PM, Robby Findler wrote: >> This is heavily relied on. >> >> Robby >> >> On Tue, May 1, 2012 at 6:45 PM, Jon Rafkind <rafk...@cs.utah.edu> wrote: >>> The default matching behavior of patterns in redex will try to match >>> duplicate pattern variables to the same term. Thus >>> >>> #lang racket >>> >>> (require redex) >>> >>> (define-language Z [x integer]) >>> (define-metafunction Z >>> simple : integer integer -> integer >>> [(simple integer integer) 1]) >>> >>> (term (simple 1 2)) >>>> simple: no clauses matched for (simple 1 2) >>> Won't match because the pattern (simple integer integer) will match the >>> first `integer' to 1, and wants to the second reference to `integer' to the >>> same thing. To get it to work I need to adorn the pattern variables with _1 >>> and _2 to make them unique. >>> >>> (define-language Z [x integer]) >>> (define-metafunction Z >>> simple : integer integer -> integer >>> [(simple integer_1 integer_2) 1]) >>> >>> I would prefer (if possible) if the default behavior treated unadorned >>> pattern variables as fresh so that I don't have to remember to attach a >>> suffix. I guess this might break existing programs but I can't imagine >>> anyone really relies on this behavior (unadorned variables matching >>> duplicate terms). >>> ____________________ >>> Racket Users list: >>> http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
