William D Clinger wrote:
> In my view, the primary
> rationale for the type-specific operations is to improve the
> portability and predictability of Scheme code.  The fixnum
> and flonum operations do that by providing a portable base
> for a portable implementation of the full numeric tower.
> This will allow Scheme programmers to use generic arithmetic
> without worrying about implementations that don't provide the
> full tower,

Would in not be simpler to allow implementations to do more or less what
they want in the base language but mandate that the full tower be
available in the library? For example, an implementation might implement
fixnums and bignums in the base language (since for many problems
ratnums, flonums, and complex numbers are not necessary) and then
provide all of the rest of the tower in the library.

In other words, why force us to have these *horrible* flonums in the
base language.

(And lest I be accused of advocating the goring someone elses ox, I say
that as someone who writes a lot of code with flonums.)

> As for assumption 3, type declarations cannot address the
> portability and predictability issues unless implementations
> are required to interpret those declarations in a consistent
> way. [And this has consequences for interpreters.]

I presume you refer to whether an implementation signals an error when
the type of an expression does not agree with its type declaration.
Isn't the choice of signalling or not signalling essentially identical
to the choice of running the SRFI-77 procedures in safe or unsafe mode?

Type declarations have the huge advantage of being potentially a general
mechanism for providing information on expression types. SRFI-77
provides a specific solution for fixnums and flonums only. Are fixnums
and flonums sufficiently more important that the other Scheme data types
to warrant this ad-hoc approach?

Regards,

Alan
--
Dr Alan Watson
Centro de Radioastronomía y Astrofísica
Universidad Astronómico Nacional de México