Correction #2:
(thx Eric, Gabriele, Joel)
> any-type ; undecidable
> any-function ; mutable
> action ; mutable (change third ...)
> function ; mutable (change first ...)
> native ; mutable (change third ...)
> op ; mutable (change third ...)
> any-word ; undecidable
> get-word ; immutable - (an immutable ref. to a mutable
word?)
> lit-word ; immutable - (an immutable ref. to a mutable
word?)
> refinement ; immutable - (an immutable ref. to a mutable
word?)
> set-word ; immutable
> word ; mutable (protect/unprotect/set ...)
> bitset ; immutable
> char ; immutable - scalar
> date ; immutable - scalar
> error ; immutable
> logic ; immutable - scalar
> money ; immutable - scalar
> none ; immutable - scalar
> number ; immutable
> integer ; immutable - scalar
> decimal ; immutable - scalar
> object ; mutable (through set-path ...)
> port ; mutable (close ...)
> series ; mutable (change ...)
> any-block ; mutable (change ...)
> block ; mutable - series (change ...)
> list ; mutable - series (change ...)
> lit-path ; mutable (change ...)
> hash ; mutable - series (change ...)
> paren ; mutable - series (change ...)
> path ; mutable - series (change ...)
> set-path ; mutable (change ...)
> 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
