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At Sat, 21 Dec 2002 21:09:29 -0500, Marc Feeley wrote: > > The distinction between `make-parameter' and `make-mutable-parameter' > > is a reasonable compromise. > > > > MzScheme can't currently support `make-mutable-parameter'. I imagine a > > revision in the near future that will allow it, > > Can't you simply use the reference implementation? You can implement > make-mutable-parameter rather easily if you have a working > make-parameter. You need to define a parameter that corresponds to > the dynamic environment, and then use that instead of the global > variable dynamic-env-local. Yes. I was thinking completely backward. A programmer could also put a mutable value inside a `make-parameter' to get the same expressiveness, right? I find this line of reasoning so compelling that I now advocate the elimination of `make-mutable-parameter'. FWIW, I found your arguments in favor of `make-mutable-parameter' uncompelling: no particular use for it, but seems on the surface to be easier to implement, etc. These sort of arguments seem suspiciously like the ones that support dynamic scope over lexical scope. Matthew