Added Signal.share

Author: robertdp

src/Wire/Signal.purs

@@ -41,6 +41,16 @@ event (Signal s) = s.event
 read :: Signal ~> Effect
 read (Signal s) = s.read
 
+share :: forall a. Signal a -> Effect (Signal a)
+share (Signal s) = do
+  shared <- Event.create
+  value <- Ref.new =<< s.read
+  _ <-
+    Event.subscribe s.event \a -> do
+      Ref.write a value
+      shared.push a
+  pure $ Signal { event: shared.event, read: Ref.read value }
+
 derive instance functorSignal :: Functor Signal
 
 instance applySignal :: Apply Signal where