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Aucbvax.2132 fa.works utzoo!duke!decvax!ucbvax!RYLAND@SRI-KL Mon Jul 6 04:19:44 1981 Re: capability machines From: Chris Ryland <RYLAND SRI-KL AT> Sorry, Henry, but a capability is NOT just a fancy name for a pointer in a machine that doesn't have enough address space to begin with. I was referring to capabilities in their full encapsulation sense, such that you can only manipulate an object if you have the rights to do so (encoded in the capability) and you can only do it by invoking an appropriate entry in the capability's type module. (This is only suggestive; particular implementations differ, of course.)

No, some capability machines do garbage collection. Hydra did.

Lisp is not a capability machine. Lisp is just a low-level language for a symbolic-object machine, and thus is attractive to hackers, because they can grovel with arbitrary "addresses" when they please (CADDADR, for example.) Of course, no one in their right mind would use Lisp that way today.

/Chris -------

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