On Mon, Sep 7, 2009 at 7:01 PM, Jacob Matthews<jac...@cs.uchicago.edu> wrote: > On Sun, Sep 6, 2009 at 3:14 PM, Robby > Findler<ro...@eecs.northwestern.edu> wrote: >> Right. That wouldn't be parametric. > > I think it's the contracts-don't-change-programs condition, not the > parametricity condition, that would be violated here. > > -jacob
Don't these contracts already change the program? I thought, since Robby indicated that "stacks" cannot be used as lists, these contracts would be wrapping the values in opaque structs for outside observers. Adding or removing the contracts changes how a list-implemented stack responds to list?. Or have I misunderstood the behavior of #:exists contracts? --Carl _________________________________________________ For list-related administrative tasks: http://list.cs.brown.edu/mailman/listinfo/plt-dev
