From 19650ce35b164c1af1056043dbf161a1618b7c06 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sat, 6 Dec 2014 11:15:39 -0500
Subject: signal: Add signal-sample-on.

* sly/signal.scm (signal-sample-on): New procedure.
---
 sly/signal.scm | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sly/signal.scm b/sly/signal.scm
index 8e2c64d..93e7716 100644
--- a/sly/signal.scm
+++ b/sly/signal.scm
@@ -39,7 +39,7 @@
             signal-proc
             signal-merge
             signal-zip
-            signal-map
+            signal-map signal-sample-on
             signal-negate
             signal-fold
             signal-filter
@@ -239,6 +239,11 @@ or more SIGNALS."
                          (%signal-set! self (current-value)))
                        inputs)))
 
+(define (signal-sample-on value-signal sample-signal)
+  "Create a new signal that takes on the value of VALUE-SIGNAL
+whenever SAMPLE-SIGNAL is updated."
+  (signal-map (lambda _ (signal-ref value-signal)) sample-signal))
+
 (define (signal-negate signal)
   "Create a new signal whose value is the 'not' of the value of
 SIGNAL."
-- 
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