Hi,

In message "[ruby-talk:01403] Re: Bignum aset"
    on 00/02/15, Dave Thomas <Dave / thomases.com> writes:
>     a = 2**100
>     b = 2**100
>     p a
>     p b
>     p a.id
>     p b.id
>     1267650600228229401496703205376
>     1267650600228229401496703205376
>     537680696
>     537680476
>
>
>I thought that only Fixnums were immediate.

Well, immediate and immutable are independent concept each other.
Immediate value is an implementation technic only at least on Ruby but
the immutableness is one of properties of objects.  I thinks integers
are immutable even if non-immediate because I consider a numeric is
free from its representation and integer[n] is an abbreviation of

  (("%b" % integer)[-1-n] || ?0).chr.to_i

But I may be wrong.  Your openion is reasonable if most users consider
that a numeric is a bit container. 

-- gotoken