On 14 June 2010 20:29, John Cowan <[email protected]> wrote: > David Rush scripsit: > > > This seems rather arbitrary, and wrong-headed (due to knock-on effects) > > in light of things like breaking mutable a-lists. Scheme is a language > > which allows free mutation of bindings and primitive objects. Immutable > > pairs is a big step on a slippery slope to a very different language. > > To be fair, it only breaks mutable a-lists of which the cdr is mutated; > car mutation isn't really a problem. (I agree that > mutable-car/immutable-cdr > pairs would be a Good Thing; indeed, one could view vectors as lists made > with such pairs.) >
That is so delightfully daft, I'd almost vote for it. :) > Out of curiosity, would you have similar objections to immutable strings? > That is a very good question, and i don't have a very good answer just now. I think I would object in principle, but in practice i probably wouldn't notice if you didn't tell me. I think, after 10 years of programming in Scheme that i can probably count the number of times i have mutated a string - as a string - on one hand. Although, there is one highly-branched tree structure i used that probably would have run in rather less space if i'd used strings instead of vectors. So to summarize, i suspect that the incidence of mutated strings in real code is several order of magnitude lower than the use of mutable cons cells and might be vanishingly small... david -- GPG Public key at http://cyber-rush.org/drr/gpg-public-key.txt
_______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
