Data commit

Task/Events/Haskell/events-1.hs

@@ -0,0 +1,11 @@
+import Control.Concurrent (threadDelay, forkIO)
+import Control.Concurrent.SampleVar
+
+-- An Event is defined as a SampleVar with no data.
+-- http://haskell.org/ghc/docs/latest/html/libraries/base/Control-Concurrent-SampleVar.html
+newtype Event = Event (SampleVar ())
+
+newEvent               = fmap Event (newEmptySampleVar)
+signalEvent (Event sv) = writeSampleVar sv ()
+resetEvent  (Event sv) = emptySampleVar sv
+waitEvent   (Event sv) = readSampleVar  sv

Task/Events/Haskell/events-2.hs

@@ -0,0 +1,11 @@
+main = do e <- newEvent
+          forkIO (waitTask e)
+          putStrLn "[1] Waiting 1 second..."
+          threadDelay 1000000 {- µs -}
+          putStrLn "[1] Signaling event."
+          signalEvent e
+          threadDelay 1000000 {- µs -}    -- defer program exit for reception
+
+waitTask e = do putStrLn "[2] Waiting for event..."
+                waitEvent e
+                putStrLn "[2] Received event."

Task/Events/Haskell/events-3.hs

@@ -0,0 +1,20 @@
+record Event(cond, value)
+
+procedure main()
+    event := Event(condvar())
+    t1 := thread {
+        write("Task one waiting for event....")
+        critical event.cond: while /(event.value) do wait(event.cond)
+        write("Task one received event.")
+        }
+    t2 := thread {
+        write("Task two waiting for event....")
+        critical event.cond: while /(event.value) do wait(event.cond)
+        write("Task two received event.")
+        }
+    delay(1000)                   # Let main thread post the event.
+    event.value := "yes"
+    write("Signalling event.")
+    signal(event.cond,0)
+    every wait(t1|t2)
+end