On Thu, Oct 20, 2011 at 10:27 PM, Ryan Culpepper <r...@cs.utah.edu> wrote: > On 10/20/2011 09:14 PM, Shriram Krishnamurthi wrote: >> >> Ryan, I noticed this seems to be a problem in full Racket as well: try >> >> #lang racket >> >> (define web-colors >> (shared ([W (cons "white" G)] >> [G (cons "grey" W)]) >> W)) >> >> (rest web-colors) >> >> Robby privately wrote to say it should be regarded as a bug. > > There seem to be conflicting intentions somewhere. Perhaps the racket/list > checks were really intended to use proper-or-cyclic-list?... except that I > think they were also put in place with the idea that list? was amortized > constant time (cached in the pair header bits). I know Eli had to make the > lazy version of first different for roughly the same reason, so maybe he can > say whether this issue was considered for racket or the teaching languages.
Conflicting intentions aside, I think that this is a bug. At best, it is a failure to document a change in the behavior, but I think it is probably just a bug. (See the commit message) Robby _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
