[Haskell-cafe] unsafeSTToIO and stToIO
xj2106 at columbia.edu
Wed Apr 29 17:26:46 EDT 2009
Between the following two functions
stToIO :: ST RealWorld a -> IO a
stToIO (ST m) = IO m
unsafeSTToIO :: ST s a -> IO a
unsafeSTToIO (ST m) = IO (unsafeCoerce# m)
All I can see is that the safe one uses RealWorld instead of
an arbitrary thread s used in the unsafe one. I really
don't understand the difference between these two. Why is
the one without RealWorld unsafe?
I tried google, but couldn't find anything helpful.
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