[Haskell-cafe] Is unsafePerformIO safe here?

John Ky newhoggy at gmail.com
Sun Dec 7 19:28:56 EST 2008


Is the following safe?

moo :: TVar Int
moo = unsafePerformIO $ newTVarIO 1

I'm interested in writing a stateful application, and I wanted to start with
writing some IO functions that did stuff on some state and then test them
over long periods of time in GHCi.

I was worried I might be depending on some guarantees that aren't actually
there, like moo being discarded and recreated inbetween invocations of
different functions.


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