define

* define - any name
@ 2003-04-19  7:22 Egil Moeller
  2003-04-20 14:58 ` Andreas Rottmann
  0 siblings, 1 reply; 10+ messages in thread
From: Egil Moeller @ 2003-04-19  7:22 UTC (permalink / raw)

At the moment, I have a function (list-entry type name), that given a
"type-definition" (a binary tree with names in), and a name, constructs a
function that will extract the entity at the position corresponding to
that name in the type, in a binary tree given as argument. The
"type-definition" i often constructed from other such definitions:

(define fride-vote-msg-type
  `(list
    (id:         ,fride-id-msg-type)
    (referendum: ,fride-id-reference-msg-type)
    (date:       int)
    (vote:       int)))

I use the list-entry function, then to construct a set of
"access-functions", e.g.

(define fride-vote-list.id (fride-list-entry fride-vote-msg-type 'id))
(define fride-vote-list.referendum (fride-list-entry fride-vote-msg-type 'referendum))

This is both quite some extra work, and also makes the code clumsier, than
if those functions could be automatically created. I'd like to write
something like

(define-type fride-vote-msg-type
  `(list
    (id:         ,fride-id-msg-type)
    (referendum: ,fride-id-reference-msg-type)
    (date:       int)
    (vote:       int)))

and have them all created. For this purpose I have created a function that
finds all names in a type-definition that can be used to create such
access-functions.

The question i, how do I go on from here? I'd like to make a macro, but
that would not let the backqoute be evaluated in the correct
environment... What I would need is a (define-unquoted-in-toplevel name
value), that would work like an ordinary funcion, evaluating its
arguments, and bind the value of name to the value of value, in the
top-level surrounding environment... Is this really not something people
have wanted before?

My idea about environments in quile is that they, due to speed
considerations or something, are a bit too limited... For example, an
eval-closure is _not_ an ordinary environment/can't be treated like one,
and one can not do (eval) with such an object as environment...

Regards,
Egil

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