diff options
Diffstat (limited to '2d/signal.scm')
-rw-r--r-- | 2d/signal.scm | 40 |
1 files changed, 36 insertions, 4 deletions
diff --git a/2d/signal.scm b/2d/signal.scm index 272cbfb..53f676a 100644 --- a/2d/signal.scm +++ b/2d/signal.scm @@ -25,15 +25,13 @@ #:use-module (srfi srfi-1) #:use-module (srfi srfi-9) #:use-module (srfi srfi-26) + #:use-module (2d agenda) #:export (signal? signal-box? make-signal - make-boxed-signal define-signal - %signal-ref signal-ref signal-ref-maybe - %signal-set! signal-set! signal-proc signal-merge @@ -44,7 +42,10 @@ signal-reject signal-constant signal-count - signal-do)) + signal-do + signal-sample + signal-delay + signal-throttle)) ;;; ;;; Signals @@ -227,3 +228,34 @@ from SIGNAL. The value of the new signal will always be the value of SIGNAL. This signal is a convenient way to sneak a procedure that has a side-effect into a signal chain." (signal-map (lambda (x) (proc x) x) signal)) + +(define (signal-sample agenda delay signal) + "Create a new signal that emits the value contained within SIGNAL +every DELAY ticks of AGENDA." + (let ((sampler (%make-signal (signal-ref signal) #f '()))) + (define (tick) + (%signal-set! sampler (signal-ref signal))) + (schedule-interval agenda tick delay) + (make-signal-box sampler))) + +(define (signal-delay agenda delay signal) + "Create a new signal that delays propagation of SIGNAL by DELAY +ticks of AGENDA." + (make-boxed-signal (signal-ref signal) + (lambda (self value) + (schedule agenda + (lambda () + (%signal-set! self value)) + delay)) + (list signal))) + +(define (signal-throttle agenda delay signal) + "Return a new signal that propagates SIGNAL at most once every DELAY +ticks of AGENDA." + (make-boxed-signal (signal-ref signal) + (let ((last-time (agenda-time agenda))) + (lambda (self value) + (when (>= (- (agenda-time agenda) last-time) delay) + (%signal-set! self value) + (set! last-time (agenda-time agenda))))) + (list signal))) |