IOEnv

data IOEnv env a

failM

failWithM

data IOEnvFailure

getEnv

setEnv

updEnv

runIOEnv

unsafeInterleaveM

tryM

tryAllM

tryMostM

fixM

data IORef a

newMutVar

readMutVar

writeMutVar

updMutVar

atomicUpdMutVar

atomicUpdMutVar'