A-M baby

Task/Jensens-Device/Haskell/jensens-device.hs

@@ -0,0 +1,13 @@
+import Control.Monad
+import Control.Monad.ST
+import Data.STRef
+
+sum' ref_i lo hi term =
+  return sum `ap`
+         mapM (\i -> writeSTRef ref_i i >> term) [lo..hi]
+
+foo = runST $ do
+        i <- newSTRef undefined -- initial value doesn't matter
+        sum' i 1 100 $ return recip `ap` readSTRef i
+
+main = print foo