Mutable/immutable Rebol values.
Adding a correction and examples how you can change the state of
mutables.
The relations:
mutable <=> series
immutable <=> scalar
are pure coincidence, because you can have immutable series and
mutable scalars. It is simply a matter of preferences of the
implementor. You can see it looking at action/native/op - all of
them contain some series - arg descriptions, yet they are
immutable. If Rebol Tech. decide, that for the function F first :f
second :f and third :f shall return deep copies of the respective
blocks, then some functions will be immutable as a consequence.
(and that is not the only way how to make some functions
immutable).
Mutable are the Rebol values, that can change their
state. (more like a storage than like a value in a sense)
Immutable are the Rebol values that cannot change their state.
(really
values in a sense)
> any-type ; undecidable
> any-function ; undecidable
> action ; immutable
> function ; mutable (change first ...)
> native ; immutable
> op ; immutable
> any-word ; mutable (bind ...)
> get-word ; mutable (bind ...)
> lit-word ; mutable (bind ...)
> refinement ; mutable (bind ...)
> set-word ; mutable (bind ...)
> word ; mutable (bind ...)
> bitset ; immutable
> char ; immutable - scalar
> date ; immutable - scalar
> error ; mutable (disarm ...)
> logic ; immutable - scalar
> money ; immutable - scalar
> none ; immutable - scalar
> number ; immutable
> integer ; immutable - scalar
> decimal ; immutable - scalar
> object ; mutable (a/x: ...)
> port ; mutable (close ...)
> series ; undecidable
> any-block ; undecidable - corrected
> block ; mutable - series (change ...)
> list ; mutable - series (change ...)
> lit-path ; immutable
> hash ; mutable - series (change ...)
> paren ; mutable - series (change ...)
> path ; immutable - series
> set-path ; immutable
> any-string ; mutable (change ...)
> binary ; mutable - series (change ...)
> email ; mutable - series (change ...)
> file ; mutable - series (change ...)
> issue ; mutable - series (change ...)
> string ; mutable - series (change ...)
> tag ; mutable - series (change ...)
> url ; mutable - series (change ...)
> symbol ; immutable
> time ; immutable - scalar
> tuple ; immutable - scalar
> unset ; immutable
