Re: Immediate doubles (up to 2^256) and rationals coming to Guile 3

[Mark H Weaver]

Ludovic Courtès <address@hidden> writes:
> Though an immediate, like a fixnum or an iflo, is still something
> different from a tagged heap object like a pair, right?

I should clarify that in this new approach, a pair is *not* a tagged
heap object.  Tagged heap objects are those which have a tag in their
first word.  In this new approach, pairs are not tagged in this sense,
and it is no longer possible to distinguish a pair from a non-pair by
looking at their raw heap blocks.

Tagged heap objects (thobs) have 000 in the low 3 bits of the SCM.
Pairs have 0110 in the low 4 bits of the SCM.

    Regards,
      Mark