109 lines
3.2 KiB
Scheme
109 lines
3.2 KiB
Scheme
|
; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
; Accessing packages
|
||
|
|
|
||
|
|
(define (environment-ref package name)
|
||
|
|
(carefully (package-lookup package name)
|
||
|
|
(lambda (loc)
|
||
|
|
(if (location-assigned? loc)
|
||
|
|
(contents loc)
|
||
|
|
(error "uninitialized variable" name package)))
|
||
|
|
package
|
||
|
|
name))
|
||
|
|
|
||
|
|
(define (environment-set! package name value)
|
||
|
|
(let ((binding (package-lookup package name)))
|
||
|
|
(if (and (binding? binding)
|
||
|
|
(not (variable-type? (binding-type binding))))
|
||
|
|
(error "invalid assignment" name package value)
|
||
|
|
(carefully binding
|
||
|
|
(lambda (loc)
|
||
|
|
(set-contents! loc value))
|
||
|
|
package name))))
|
||
|
|
|
||
|
|
(define (environment-define! package name value)
|
||
|
|
(set-contents! (package-define! package name usual-variable-type #f #f)
|
||
|
|
value))
|
||
|
|
|
||
|
|
(define (*structure-ref struct name)
|
||
|
|
(let ((binding (structure-lookup struct name #f)))
|
||
|
|
(if binding
|
||
|
|
(carefully binding contents struct name)
|
||
|
|
(error "structure-ref: name not exported" struct name))))
|
||
|
|
|
||
|
|
(define (carefully binding action env name)
|
||
|
|
(cond ((not binding)
|
||
|
|
(error "unbound variable" name env))
|
||
|
|
((not (binding? binding))
|
||
|
|
(error "peculiar binding" binding name env))
|
||
|
|
((eq? (binding-type binding) syntax-type)
|
||
|
|
(error "attempt to reference syntax as variable" name env))
|
||
|
|
(else
|
||
|
|
(let ((loc (binding-place binding)))
|
||
|
|
(if (location? loc)
|
||
|
|
(if (location-defined? loc)
|
||
|
|
(action loc)
|
||
|
|
(error "unbound variable" name env))
|
||
|
|
(error "variable has no location" name env))))))
|
||
|
|
|
||
|
|
; Interaction environment
|
||
|
|
|
||
|
|
(define $interaction-environment (make-fluid #f))
|
||
|
|
|
||
|
|
(define (interaction-environment)
|
||
|
|
(fluid $interaction-environment))
|
||
|
|
|
||
|
|
(define (set-interaction-environment! p)
|
||
|
|
(if (package? p)
|
||
|
|
(set-fluid! $interaction-environment p)
|
||
|
|
(call-error "invalid package" set-interaction-environment! p)))
|
||
|
|
|
||
|
|
(define (with-interaction-environment p thunk)
|
||
|
|
(if (package? p)
|
||
|
|
(let-fluid $interaction-environment p thunk)
|
||
|
|
(call-error "invalid package" with-interaction-environment p)))
|
||
|
|
|
||
|
|
|
||
|
|
; Scheme report environment. Should be read-only; fix later.
|
||
|
|
|
||
|
|
(define (scheme-report-environment n)
|
||
|
|
(if (= n *scheme-report-number*)
|
||
|
|
*scheme-report-environment*
|
||
|
|
(error "no such Scheme report environment")))
|
||
|
|
|
||
|
|
(define *scheme-report-environment* #f)
|
||
|
|
(define *null-environment* #f)
|
||
|
|
(define *scheme-report-number* 0)
|
||
|
|
|
||
|
|
(define (set-scheme-report-environment! repnum env)
|
||
|
|
(set! *scheme-report-number* repnum)
|
||
|
|
(set! *scheme-report-environment* env)
|
||
|
|
(set! *null-environment* env)) ; A cheat.
|
||
|
|
|
||
|
|
(define (null-environment n)
|
||
|
|
(if (= n *scheme-report-number*)
|
||
|
|
*null-environment*
|
||
|
|
(error "no such Scheme report environment")))
|
||
|
|
|
||
|
|
; Make an infinite tower of packages for syntax.
|
||
|
|
; structs should be a non-null list of structures that should be
|
||
|
|
; opened at EVERY level of the tower.
|
||
|
|
|
||
|
|
(define (make-reflective-tower eval structs id)
|
||
|
|
(let recur ((level 1))
|
||
|
|
(delay (cons eval
|
||
|
|
(make-simple-package structs
|
||
|
|
eval
|
||
|
|
(recur (+ level 1))
|
||
|
|
`(for-syntax ,level ,id))))))
|
||
|
|
|
||
|
|
; (set-reflective-tower-maker! p (lambda (clauses id) ...))
|
||
|
|
; where clauses is a list of DEFINE-STRUCTURE clauses
|
||
|
|
|
||
|
|
(define set-reflective-tower-maker!
|
||
|
|
(let ((name (string->symbol ".make-reflective-tower.")))
|
||
|
|
(lambda (p proc)
|
||
|
|
(environment-define! p name proc))))
|