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[REBOL] Re: On mutability and sameness

From: sanghabum:aol at: 6-Jun-2001 5:05

Hi Ladislav,
> I am pretty sure, that the feature you are describing is not a bug. The > reason for the behaviour is pretty simple. Rebol values of type TUPLE!
> INTEGER! and some other types are immutable - Mark Dickson uses the word > constant to express the same feature. What does the strange word mean? No > Rebol function can change these values. Example: <snip>
Bug, feature, or quirk --- any of them are acceptable. But if it is a feature (and if it is, it's a fairly fundamental one), it would help if the documentation mentioned it. The users' guide's simply says there are two fundamental datatypes: scalars and series. We now seem to be discovering each of these can be mutable or immutable. That leaves me with a much more complex model of what is going on. Add in the fact that Poke will operate on a two-part item like Money!, but not on a two-part item like Pair! and some of the dazzling simplicity starts to slip away....I now have to remember to use Poke in two different ways: Poke MyBlock 2 5 ;;--to update a Block MyTuple: poke MyTuple 2 5 ;; -- to update a Tuple Plus, I can't use it at all on a Pair, so I need to write: Mypair/2: 5 ;;-- to update a Pair Thanks for the analysis, --Colin.