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diff --git a/files/practicum/StdStateMonad.icl b/files/practicum/StdStateMonad.icl
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+++ b/files/practicum/StdStateMonad.icl
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+implementation module StdStateMonad
+
+import StdMonad
+
+:: ST s a = ST (s -> (a, s))
+
+instance return (ST s) where return x     = ST (\w = (x, w))
+instance >>=    (ST s) where >>= (ST f) g = ST (\w = let (a, w1) = f w 
+                                                      in unST (g a) w1
+                                               )
+
+mkST :: (s -> (a,s)) -> ST s a
+mkST f = ST f
+
+unST :: (ST s a) -> s -> (a, s)
+unST (ST f) = f