Integer Shift Function(s)

["Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>]

All of the logical operations are defined in terms of an abstract
integer type that is infinitely sign-extended to the left.  That way,
the machine's word-length, or the length of the data part of its fixnum
representation, is hidden.  What would a logical shift operation (or a
rotate, though you don't ask about that) do in this context?

An implementation may want to define LSH and ROT operations for its own
peculiar fixnum length, but such a thing makes no sense in portable
code.

-- Scott