[Haskell-cafe] How to Hijack stdin,err,out, thread safely?

[Hiromi ISHII]

Hi,

I'm currently writing a web app to check the spec of input code
usging QuickCheck.
quickCheck* functions writes results to stderr & stdout, but I
don't want them written to the app's original stdout/err.
(I'm using SafeHaskell features to avoid malicious code executed,
so don't worry about that :-))

So I want to execute I/O action hijacking stdout/err in a thread-safe manner.
For example, I need function like below:

censorHandles :: IO a -> IO (a, String, String)
censorHandles = ...

or

withStd :: Handle -> Handle -> Handle -> IO a -> IO a
withStd = ...

-- Hiromi ISHII
konn.jinro at gmail.com



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