On Fri, Jun 10, 2011 at 7:03 PM, Richard Lawrence <richard.lawre...@berkeley.edu> wrote: > Sam Tobin-Hochstadt <sa...@ccs.neu.edu> > writes: > >> I'll try to respond more comprehensively about the more general >> question, but for this: >>> (define-type Variable (Pair 'var Symbol)) >>> (define-predicate variable? Variable) >> >> Just use a struct: >> >> (struct: variable ([s : Symbol])) >> >> Now you have `variable' and `variable?' and `variable-s', and there's >> no confusion with pairs. That's how I'd write this code. > > Ah, duh. Thanks, Sam. (I take it this means that the answer to my more > general question is, ``No, you can't do that,'' but I'll be interested > to read your response when you've got time to send it.)
As it turns out, the answer to the more general question is: we have an experimental mechanism to do that, called refinement types, that seems to be currently broken. Once I fix it, I'll respond again. -- sam th sa...@ccs.neu.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
