Re: SCM_VALIDATE_...

[Dirk Herrmann <dirk at ida dot ing dot tu-bs dot de>]

On 25 May 2000, Mikael Djurfeldt wrote:

> Also note that I didn't say we should freeze te entire hierarchy.  I
> *do* think it would be good t freeze <integer>, <fixnum>, and,
> <bignum>, though.

I'm a little sceptical about whether it makes sense to freeze integer.  I
understand the point about fixnums and bignums, because these are leaves
in the class tree corresponding to implementations.  As I understand it, a
class tree might then look as follows:

<number>
  <complex>
    <comp-rep*>
    <real>
      <float*>
      <double*>
      <rational>
        <rat-rep*>
        <integer>
          <bignum*>
          <fixnum*>

Types with * denote representations, some of which don't even exist
yet.  (Mikael, in your version of the class tree, fixnums were a subclass
of bignums.  I assume this was a mistake?)

If we disallow subclassing of integers, then we would, for example,
disallow the implementation of a modulo-arithmetic type as an additional
representation besides bignums and fixnums.  Also, integer range types
like n-bit integer values (like for uniform vectors as defined in some 
SRFI) or integers from a certain interval etc.

So, I think it would be a loss to disallow subclassing of integer.  Maybe
an intermediate class <guile-integer-rep> or so which covers only guile's
internal integer representations would help?

<number>
  <complex>
    <comp-rep*>
    <real>
      <float*>
      <double*>
      <rational>
        <rat-rep*>
        <integer>
          <user-int-rep1>
          <user-int-rep2>
          <...>
          <guile-integer-rep>
            <bignum*>
            <fixnum*>

Best regards
Dirk