summaryrefslogtreecommitdiff
path: root/module/srfi/srfi-39.scm
diff options
context:
space:
mode:
Diffstat (limited to 'module/srfi/srfi-39.scm')
-rw-r--r--module/srfi/srfi-39.scm101
1 files changed, 8 insertions, 93 deletions
diff --git a/module/srfi/srfi-39.scm b/module/srfi/srfi-39.scm
index d1c46d028..0d540633d 100644
--- a/module/srfi/srfi-39.scm
+++ b/module/srfi/srfi-39.scm
@@ -35,104 +35,19 @@
;;; Code:
(define-module (srfi srfi-39)
- #:use-module (srfi srfi-16)
-
- #:export (make-parameter)
- #:export-syntax (parameterize)
-
;; helper procedure not in srfi-39.
#:export (with-parameters*)
- #:replace (current-input-port current-output-port current-error-port))
-
-;; Make 'srfi-39 available as a feature identifiere to `cond-expand'.
-;;
-(cond-expand-provide (current-module) '(srfi-39))
-
-(define make-parameter
- (case-lambda
- ((val) (make-parameter/helper val (lambda (x) x)))
- ((val conv) (make-parameter/helper val conv))))
-
-(define get-fluid-tag (lambda () 'get-fluid)) ;; arbitrary unique (as per eq?) value
-(define get-conv-tag (lambda () 'get-conv)) ;; arbitrary unique (as per eq?) value
-
-(define (make-parameter/helper val conv)
- (let ((fluid (make-fluid (conv val))))
- (case-lambda
- (()
- (fluid-ref fluid))
- ((new-value)
- (cond
- ((eq? new-value get-fluid-tag) fluid)
- ((eq? new-value get-conv-tag) conv)
- (else (fluid-set! fluid (conv new-value))))))))
-
-(define-syntax-rule (parameterize ((?param ?value) ...) ?body ...)
- (with-parameters* (list ?param ...)
- (list ?value ...)
- (lambda () ?body ...)))
+ #:re-export (make-parameter
+ parameterize
+ current-input-port current-output-port current-error-port))
-(define current-input-port
- (case-lambda
- (()
- ((@ (guile) current-input-port)))
- ((new-value)
- (set-current-input-port new-value))))
-
-(define current-output-port
- (case-lambda
- (()
- ((@ (guile) current-output-port)))
- ((new-value)
- (set-current-output-port new-value))))
-
-(define current-error-port
- (case-lambda
- (()
- ((@ (guile) current-error-port)))
- ((new-value)
- (set-current-error-port new-value))))
-
-(define port-list
- (list current-input-port current-output-port current-error-port))
-
-;; There are no fluids behind current-input-port etc, so those parameter
-;; objects are picked out of the list and handled separately with a
-;; dynamic-wind to swap their values to and from a location (the "value"
-;; variable in the swapper procedure "let").
-;;
-;; current-input-port etc are already per-dynamic-root, so this arrangement
-;; works the same as a fluid. Perhaps they could become fluids for ease of
-;; implementation here.
-;;
-;; Notice the use of a param local variable for the swapper procedure. It
-;; ensures any application changes to the PARAMS list won't affect the
-;; winding.
-;;
(define (with-parameters* params values thunk)
(let more ((params params)
(values values)
(fluids '()) ;; fluids from each of PARAMS
- (convs '()) ;; VALUES with conversion proc applied
- (swapper noop)) ;; wind/unwind procedure for ports handling
+ (convs '())) ;; VALUES with conversion proc applied
(if (null? params)
- (if (eq? noop swapper)
- (with-fluids* fluids convs thunk)
- (dynamic-wind
- swapper
- (lambda ()
- (with-fluids* fluids convs thunk))
- swapper))
- (if (memq (car params) port-list)
- (more (cdr params) (cdr values)
- fluids convs
- (let ((param (car params))
- (value (car values))
- (prev-swapper swapper))
- (lambda ()
- (set! value (param value))
- (prev-swapper))))
- (more (cdr params) (cdr values)
- (cons ((car params) get-fluid-tag) fluids)
- (cons (((car params) get-conv-tag) (car values)) convs)
- swapper)))))
+ (with-fluids* fluids convs thunk)
+ (more (cdr params) (cdr values)
+ (cons (parameter-fluid (car params)) fluids)
+ (cons ((parameter-converter (car params)) (car values)) convs)))))