Add trivial clock

rhine/rhine.cabal

@@ -109,6 +109,7 @@ library
     FRP.Rhine.Clock.Realtime.Never
     FRP.Rhine.Clock.Realtime.Stdin
     FRP.Rhine.Clock.Select
+    FRP.Rhine.Clock.Trivial
     FRP.Rhine.Clock.Unschedule
     FRP.Rhine.Clock.Util
     FRP.Rhine.Reactimation

rhine/src/FRP/Rhine.hs

@@ -41,6 +41,7 @@ import FRP.Rhine.Clock.Realtime.Millisecond as X
 import FRP.Rhine.Clock.Realtime.Never as X
 import FRP.Rhine.Clock.Realtime.Stdin as X
 import FRP.Rhine.Clock.Select as X
+import FRP.Rhine.Clock.Trivial as X
 import FRP.Rhine.Clock.Unschedule as X
 
 import FRP.Rhine.ResamplingBuffer.Collect as X

rhine/src/FRP/Rhine/Clock/Trivial.hs

@@ -0,0 +1,18 @@
+module FRP.Rhine.Clock.Trivial where
+
+-- base
+import Control.Arrow
+
+-- rhine
+import FRP.Rhine.Clock
+import FRP.Rhine.Clock.Proxy (GetClockProxy)
+
+-- | A clock that always returns the tick '()'.
+data Trivial = Trivial
+
+instance (Monad m) => Clock m Trivial where
+  type Time Trivial = ()
+  type Tag Trivial = ()
+  initClock _ = return (arr $ const ((), ()), ())
+
+instance GetClockProxy Trivial