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| author | David Thompson <dthompson2@worcester.edu> | 2016-02-10 21:58:41 -0500 |
|---|---|---|
| committer | David Thompson <dthompson2@worcester.edu> | 2016-02-10 22:01:38 -0500 |
| commit | f36ee4549eca5a6754289befdda9bf9cc93a0ee9 (patch) | |
| tree | 800f3bfbf4583ea875aae9803f586dfff095edaa | |
| parent | c42111ad39d4b1ebef3d02d207e1f6bfa0d4022d (diff) | |
signal: Add signal-if.
* sly/signal.scm (signal-if): New syntax.
| -rw-r--r-- | sly/signal.scm | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sly/signal.scm b/sly/signal.scm index 5bd9a29..42cce40 100644 --- a/sly/signal.scm +++ b/sly/signal.scm @@ -48,6 +48,7 @@ signal-drop signal-drop-repeats signal-switch + signal-if signal-constant signal-count signal-tap @@ -341,6 +342,9 @@ signal PRED is true, or the value of the signal OFF otherwise." (%signal-set! self (current-value))) (list predicate))) +(define-syntax-rule (signal-if predicate consequent alternate) + (signal-map (lambda (true?) (if true? consequent alternate)) predicate)) + (define (signal-constant constant signal) "Create a new signal whose value is always CONSTANT no matter the value of SIGNAL." |