1 import Control.Monad.X.Writer
4 t1 = test (tell "x") ((),"x")
5 t2 = test (listen (tell "x")) (((),"x"),"")
8 (_,y) <- listen (tell "y")
13 t4 = test (listen (listen (tell "x"))) ((((),"x"),""),"")
15 test m e = runWriter m == e
17 main = print $ and [t1,t2,t3,t4]