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|
#| Copyright (C) 2025 Peter McGoron
|
| Permission is hereby granted, free of charge, to any person obtaining a
| copy of this software and associated documentation files (the
| "Software"), to deal in the Software without restriction, including
| without limitation the rights to use, copy, modify, merge, publish,
| distribute, sublicense, and/or sell copies of the Software, and to
| permit persons to whom the Software is furnished to do so, subject to
| the following conditions:
|
| The above copyright notice and this permission notice (including the
| next paragraph) shall be included in all copies or substantial portions
| of the Software.
|
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
| OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
| MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
| IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
| CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
| TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
| SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|#
(define is-type? (condition-predicate 'type))
(define (create-predicate id)
(lambda (proc)
(cond
((not (procedure? proc)) #f)
((get-mapping proc)
=> (cut fxmapping-contains? <> id))
(else #f))))
(define (create-accessor id)
(lambda (proc)
(define map
(handle-exceptions E (abort
(make-composite-condition
(make-property-condition
'exn
'location
(quote accessor)
'arguments
(list proc)
'message
"not a procedure")
E))
(get-mapping proc)))
(define (raise-error)
(abort
(make-composite-condition
(make-property-condition 'exn
'location
(quote accessor)
'arguments
(list proc)
'message
"tag was not found")
(make-property-condition 'assertion))))
(if map
(fxmapping-ref map id raise-error)
(raise-error))))
;;; ;;;;;;;;;;;;;;;
;;; Bootstrapping
;;; ;;;;;;;;;;;;;;;
(define get-base-procedure (create-accessor 0))
(define tagged-procedure? (create-predicate 0))
(define procedure/self-tag -1)
(define procedure/self? (create-predicate procedure/self-tag))
(define (create-constructor id)
(lambda (tag proc)
(cond
((not (procedure? proc))
(abort (make-composite-condition
(make-property-condition
'exn
'location
(quote constructor)
'arguments
(list proc)
'message
"not a procedure")
(make-property-condition
'type
'value
proc))))
((procedure/self? proc)
(letrec* ((base (get-base-procedure proc))
(nproc
(create/signifier-pair (lambda args
(apply base nproc args))
(make-signifier
(fxmapping-set (get-mapping proc)
id
tag)))))
nproc))
((tagged-procedure? proc)
(let ((map (get-mapping proc)))
(set-signifier-pair proc
unique-symbol
(make-signifier
(fxmapping-set map id tag)))))
(else (create/signifier-pair proc
(make-signifier
(fxmapping id tag
0 proc)))))))
(define tag/this (create-constructor -1))
(define-syntax define-procedure-tag
(syntax-rules ()
((define-procedure-tag constructor predicate? accessor)
;; This uses `define-values` instead of a define for `id` because
;; Chicken breaks hygiene for top-level `define` names.
(define-values (constructor predicate? accessor)
(let ((id (unique-id)))
(values
(create-constructor id)
(create-predicate id)
(create-accessor id)))))))
(define-syntax lambda/this
(syntax-rules ()
((lambda/this this formal body ...)
;; Quick hack to make the constructor work. Should fix.
(tag/this #f
(tag/this #f
(lambda (this . formal) body ...))))))
(define-syntax define/this
(syntax-rules ()
((define/this (name this . args) body ...)
(define name (lambda/this this args body ...)))))
|
