diff options
Diffstat (limited to '2d')
| -rw-r--r-- | 2d/signals.scm | 125 |
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)) |