diff options
| -rw-r--r-- | sly/signal.scm | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/sly/signal.scm b/sly/signal.scm index f8545eb..3e5ce26 100644 --- a/sly/signal.scm +++ b/sly/signal.scm @@ -41,6 +41,7 @@ signal-filter signal-reject signal-drop-repeats + signal-switch signal-constant signal-count signal-tap @@ -258,6 +259,18 @@ testing equivalence." (signal-ref signal) signal)) +(define (signal-switch pred on off) + "Create a new signal whose value is that of the signal ON when the +signal PRED is true, or the value of the signal OFF otherwise." + (define (current-value) + (if (signal-ref pred) + (signal-ref on) + (signal-ref off))) + (make-boxed-signal (current-value) + (lambda (self value) + (%signal-set! self (current-value))) + (list pred))) + (define (signal-constant constant signal) "Create a new signal whose value is always CONSTANT regardless of what the value received from SIGNAL." |