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-rw-r--r--2d/signals.scm142
1 files changed, 76 insertions, 66 deletions
diff --git a/2d/signals.scm b/2d/signals.scm
index 39e4d86..0265973 100644
--- a/2d/signals.scm
+++ b/2d/signals.scm
@@ -38,7 +38,6 @@
signal-disconnect!
signal-clear!
signal-set!
- signal-identity
signal-constant
signal-lift
signal-lift2
@@ -68,12 +67,19 @@
(filter signal-filter)
(connectors signal-connectors %set-signal-connectors!))
+(define (identity-transform value old from)
+ "Return VALUE unchanged."
+ value)
+
(define (keep-all value old from)
"Keep all values."
#t)
-(define* (make-signal transformer #:optional #:key
- (init #f) (connectors '()) (filter keep-all))
+(define* (make-signal #:optional #:key
+ (transformer identity-transform)
+ (filter keep-all)
+ (init #f)
+ (connectors '()))
"Create a new signal with initial value INIT that uses the given
TRANSFORMER procedure to process incoming values from another
signal. Additionally, the signal will be connected to all of the
@@ -138,111 +144,115 @@ will be set if it passes through the filter."
;;; Primitive signals
;;;
-(define* (signal-identity #:optional (init #f))
- "Create a new signal with initial value INIT whose transformer procedure
-returns values unchanged."
- (make-signal (lambda (value prev from)
- value)
- #:init init))
-
(define (signal-constant constant)
"Create a new signal with a value CONSTANT that cannot be changed."
- (make-signal (lambda (value prev from)
- constant)
- #:init constant))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ 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."
- (make-signal (lambda (value prev from)
- (transformer value))
- #:connectors (list signal)))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (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."
- (make-signal (lambda (value prev from)
- (transformer (signal-ref signal1)
- (signal-ref signal2)))
- #:connectors (list signal1 signal2)))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (transformer (signal-ref signal1)
+ (signal-ref signal2)))
+ #:connectors (list signal1 signal2)))
(define (signal-lift3 transformer signal1 signal2 signal3)
"Create a new signal that lifts the procedure TRANSFORMER of arity 3
onto SIGNAL1, SIGNAL2, and SIGNAL3."
- (make-signal (lambda (value prev from)
- (transformer (signal-ref signal1)
- (signal-ref signal2)
- (signal-ref signal3)))
- #:connectors (list signal1 signal2 signal3)))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (transformer (signal-ref signal1)
+ (signal-ref signal2)
+ (signal-ref signal3)))
+ #:connectors (list signal1 signal2 signal3)))
(define (signal-lift4 transformer signal1 signal2 signal3 signal4)
"Create a new signal that lifts the procedure TRANSFORMER of arity 4
onto SIGNAL1, SIGNAL2, SIGNAL3, and SIGNAL4."
- (make-signal (lambda (value prev from)
- (transformer (signal-ref signal1)
- (signal-ref signal2)
- (signal-ref signal3)
- (signal-ref signal4)))
- #:connectors (list signal1 signal2 signal3 signal4)))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (transformer (signal-ref signal1)
+ (signal-ref signal2)
+ (signal-ref signal3)
+ (signal-ref signal4)))
+ #:connectors (list signal1 signal2 signal3 signal4)))
(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."
- (make-signal (lambda (value prev from)
- value)
- #:connectors (list signal1 signal2)))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ value)
+ #:connectors (list signal1 signal2)))
(define (signal-combine . signals)
"Create a new signal that combines the values of SIGNALS into a
list."
- (make-signal (lambda (value prev from)
- (map signal-ref signals))
- #:connectors signals))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (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."
- (make-signal (lambda (value prev from)
- (1+ prev))
- #:connectors (list signal)))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (1+ prev))
+ #: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."
- (make-signal (lambda (value prev from)
- (if (signal-ref predicate)
- (signal-ref consequent)
- (signal-ref alternate)))
- #:connectors (list predicate
- consequent
- alternate)))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (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."
- (make-signal (lambda (value prev from)
- (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))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (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."
- (make-signal (lambda (value prev from)
- (let loop ((signals signals))
- (cond ((null? signals)
- #f)
- ((signal-ref (car signals))
- (signal-ref (car signals)))
- (else
- (loop (cdr signals))))))
- #:connectors signals))
+ (make-signal
+ #:transformer (lambda (value prev from)
+ (let loop ((signals signals))
+ (cond ((null? signals)
+ #f)
+ ((signal-ref (car signals))
+ (signal-ref (car signals)))
+ (else
+ (loop (cdr signals))))))
+ #:connectors signals))