Implementing a "write" method for self-evaluating objects (by equal?)

[divoplade <d@divoplade.fr>]

Hello guile users,

In the manual, I read:

(define-method (write (file <named-file>) port)
  (format port "#<<file> ~s ~a>" (name file) (fd file)))

So it is possible to define a write method for foreign objects (and
more generally GOOPS classes).

My question is: why use such a bizarre syntax with # and <? Would it
not be better to make it self-evaluating:

  (format port "(make <named-file> #:fd ~a #:name ~s)"
    (fd file) (name file))

This is a little more verbose, but at least the syntax explains how to
construct the value. There must be some cases where it would not be
possible (such as pointers to opaque data that do not have a
constructor...), and it would break  if for instance "make" is renamed
to something else. However, if I were to implement a write method, I
would use this, a textual representation of a constructor that would
produce the same value (according to equal?).