Thanks Hendrik for both responses - please see inline. On Wed, Dec 1, 2010 at 7:23 PM, Hendrik Boom <hend...@topoi.pooq.com> wrote:
> > The immutable hash table doesn't work well for lexically scoped > variables. > > You can end up with multiple simultaneous bindings of the same > variable in different contexts. Look up the Knuth Man-or-boy problem, > for example, in http://en.wikipedia.org/wiki/Man_or_boy_test But isn't that what's called for in a chained environment? The inner can see the outer bindings if not shadowed, but not vice versa. > Subsituting them away is a correct, but slow way of implementing lexical > scoping. It was invented in the days when mathematicians were inventing > formal logic, and computers weren't around yet -- more as a way of > preciely defining concepts tha a way of being practical. It had a clear > meaning before side-effects became commonplace. So what would be a fast way? > But the activation frame doesn't have to be on the stack. It could, > say, be om the heap. Yes agreed - I don't mean the frames need to be held on "the stack" - I don't even know if racket's frames are on "the stack". I just mean that I need to maintain my own stack of frames instead of relying on racket to do so. Thanks, yc
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