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-rw-r--r--2d/signals.scm125
1 files changed, 57 insertions, 68 deletions
diff --git a/2d/signals.scm b/2d/signals.scm
index ac083a3..c55c0ba 100644
--- a/2d/signals.scm
+++ b/2d/signals.scm
@@ -62,10 +62,15 @@
(transformer signal-transformer)
(listeners signal-listeners %set-signal-listeners!))
-(define* (make-signal transformer #:optional (init #f))
+(define* (make-signal transformer #:optional #:key
+ (init #f) (connectors '()))
"Create a new signal with initial value INIT that uses the given
-TRANSFORMER procedure to process incoming values from another signal."
- (%make-signal init transformer '()))
+TRANSFORMER procedure to process incoming values from another
+signal. Additionally, the signal will be connected to all of the
+signals in the list CONNECTORS."
+ (let ((signal (%make-signal init transformer '())))
+ (for-each (cut signal-connect! <> signal) connectors)
+ signal))
(define (%signal-transform signal value)
"Call the transform procedure for SIGNAL with VALUE."
@@ -103,106 +108,90 @@ signals."
(define* (signal-identity #:optional (init #f))
"Create a new signal with initial value INIT whose transformer procedure
-returns the given value unchanged."
- (make-signal (lambda (value old-value) value) init))
+returns values unchanged."
+ (make-signal (lambda (value old-value)
+ value)
+ #:init init))
(define (signal-constant constant)
"Create a new signal with a value CONSTANT that cannot be changed."
- (make-signal (lambda (value old-value signal) constant) constant))
+ (make-signal (lambda (value old-value signal)
+ constant)
+ #:init constant))
;; TODO: Write a macro for generating lifts
(define (signal-lift transformer signal)
"Create a new signal that lifts the procedure TRANSFORMER of arity 1
onto SIGNAL."
- (let ((new-signal (make-signal (lambda (value old-value)
- (transformer value)))))
- (signal-connect! signal new-signal)
- new-signal))
+ (make-signal (lambda (value old-value)
+ (transformer value))
+ #:connectors (list signal)))
(define (signal-lift2 transformer signal1 signal2)
"Create a new signal that lifts the procedure TRANSFORMER of arity 2
onto SIGNAL1 and SIGNAL2."
- (define (transform value old-value)
- (transformer (signal-ref signal1)
- (signal-ref signal2)))
-
- (let ((new-signal (make-signal transform)))
- (signal-connect! signal1 new-signal)
- (signal-connect! signal2 new-signal)
- new-signal))
+ (make-signal (lambda (value old-value)
+ (transformer (signal-ref signal1)
+ (signal-ref signal2)))
+ #:connectors (list signal1 signal2)))
(define (signal-merge signal1 signal2)
"Create a new signal that merges SIGNAL1 and SIGNAL2 into one. The
value of the new signal is the value of the most recently changed
parent signal."
- (let ((merged (signal-identity)))
- (signal-connect! signal1 merged)
- (signal-connect! signal2 merged)
- merged))
+ (make-signal (lambda (value old-value)
+ value)
+ #:connectors (list signal1 signal2)))
(define (signal-combine . signals)
"Create a new signal that combines the values of SIGNALS into a
list."
- (define (combiner value old-value)
- (map signal-ref signals))
-
- (let ((combined (make-signal combiner)))
- (for-each (cut signal-connect! <> combined) signals)
- combined))
+ (make-signal (lambda (value old-value)
+ (map signal-ref signals))
+ #:connectors signals))
(define (signal-count signal)
"Create a new signal that increments a counter every time the value
of SIGNAL changes."
- (define (increment value old-value)
- (1+ old-value))
-
- (let ((counter (make-signal increment -1)))
- (signal-connect! signal counter)
- counter))
+ (make-signal (lambda (value old-value)
+ (1+ old-value))
+ #:connectors (list signal)))
(define (signal-if predicate consequent alternate)
"Create a new signal that emits the value of the signal CONSEQUENT
when the value of the signal PREDICATE is true and the value of the
signal ALTERNATE otherwise."
- (define (transform value old-value)
- (if (signal-ref predicate)
- (signal-ref consequent)
- (signal-ref alternate)))
-
- (let ((signal (make-signal transform)))
- (signal-connect! predicate signal)
- (signal-connect! consequent signal)
- (signal-connect! alternate signal)
- signal))
+ (make-signal (lambda (value old-value)
+ (if (signal-ref predicate)
+ (signal-ref consequent)
+ (signal-ref alternate)))
+ #:connectors (list predicate
+ consequent
+ alternate)))
(define (signal-and . signals)
"Create a new signal that performs a logical AND operation on the
values of SIGNALS."
- (define (do-and signals prev)
- (cond ((null? signals)
- (signal-ref prev))
- ((signal-ref (car signals))
- (do-and (cdr signals) (car signals)))
- (else
- #f)))
-
- (let ((signal (make-signal (lambda (value old-value)
- (do-and signals #t)))))
- (for-each (cut signal-connect! <> signal) signals)
- signal))
+ (make-signal (lambda (value old-value)
+ (let loop ((signals signals)
+ (prev #t))
+ (cond ((null? signals)
+ (signal-ref prev))
+ ((signal-ref (car signals))
+ (loop (cdr signals) (car signals)))
+ (else
+ #f))))
+ #:connectors signals))
(define (signal-or . signals)
"Create a new signal that performs a logicla OR operation the values
of SIGNALS."
- (define (do-or signals)
- (cond ((null? signals)
- #f)
- ((signal-ref (car signals))
- (signal-ref (car signals)))
- (else
- (do-or (cdr signals)))))
-
- (let ((signal (make-signal (lambda (value old-value)
- (do-or signals)))))
- (for-each (cut signal-connect! <> signal) signals)
- signal))
+ (make-signal (lambda (value old-value)
+ (let loop ((signals signals))
+ (cond ((null? signals)
+ #f)
+ ((signal-ref (car signals))
+ (signal-ref (car signals)))
+ (else
+ (loop (cdr signals))))))
+ #:connectors signals))