___         ___ _
  / _ \ /\  /\/ __(_)
 / /_\// /_/ / /  | |      GHC Interactive, version 5.03, for Haskell 98.
/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
\____/\/ /_/\____/|_|      Type :? for help.

Loading package std ... linking ... done.
Prelude> -- !!! check we can detect deadlock
Prelude> :set -package concurrent
Loading package lang ... linking ... done.
Loading package concurrent ... linking ... done.
Prelude> Concurrent.newEmptyMVar >>= Concurrent.takeMVar
Deadlocked.
Prelude> Leaving GHCi.