Changes between Version 4 and Version 5 of monad-coroutine

Timestamp:

03/22/10 00:07:53 (3 years ago)

Author:

blamario (IP: 99.241.117.248)

Comment:

--

monad-coroutine

@@ -1 +1 @@
 
-= Package monad-coroutine =
+= monad-coroutine =
 
 This library, implemented by the `Control.Monad.Coroutine` module, provides a limited coroutine functionality in Haskell. The centerpiece of the approach is the monad transformer `Coroutine`, which transforms an arbitrary monadic computation into a suspendable and resumable one. The basic definition is simple:
@@ -36 +36 @@
 }}}
 
+While these two are the most obvious suspension functors, any functor whatsoever can be used as a coroutine suspension functor. See ListSuspension, for example.
+
 == Running a coroutine ==
 
+After a coroutine suspends, the suspension functor must be unpacked to get to the coroutine resumption. Here's an example of how the ''printer'' example could be run:
+
+{{{
+ printerFeeder :: Show x => [x] -> Coroutine (Await x) IO () -> IO ()
+ printerFeeder [] _ = return ()
+ printerFeeder (head:tail) printer = do p <- resume printer
+                                        case p of Left (Await p') -> printerFeeder tail (p' head)
+                                                  Right result -> return result
+}}}
+
+Alternatively, you can use the function `pogoStick` or `foldRun` to the same effect:
+
+{{{
+ printerFeeder feed printer = liftM snd $ foldRun f feed printer
+   where f (head:tail) (Await p) = (tail, p head)
+         f []          _         = ([], return ())
+}}}