Resolving dependencies...
Configuring bytestring-0.9.2.1...
Building bytestring-0.9.2.1...
Installed bytestring-0.9.2.1
Configuring unix-2.7.2.1...
Building unix-2.7.2.1...
Installed unix-2.7.2.1
Configuring entropy-0.2.2.4...
Building entropy-0.2.2.4...
Installed entropy-0.2.2.4
Configuring bcrypt-0.0.2...
Building bcrypt-0.0.2...
Failed to install bcrypt-0.0.2
Build log ( /home/builder/.cabal/logs/bcrypt-0.0.2.log ):
cabal: Entering directory '/tmp/cabal-tmp-28448/bcrypt-0.0.2'
Configuring bcrypt-0.0.2...
Building bcrypt-0.0.2...
Preprocessing library bcrypt-0.0.2...
[1 of 1] Compiling Crypto.BCrypt    ( Crypto/BCrypt.hs, dist/build/Crypto/BCrypt.o )

Crypto/BCrypt.hs:115:3: error:
    Variable not in scope:
      unsafePerformIO :: IO (Maybe BS.ByteString) -> Maybe BS.ByteString

Crypto/BCrypt.hs:141:3: error:
    Variable not in scope:
      unsafePerformIO :: IO (Maybe BS.ByteString) -> Maybe BS.ByteString
cabal: Leaving directory '/tmp/cabal-tmp-28448/bcrypt-0.0.2'
cabal: Error: some packages failed to install:
bcrypt-0.0.2 failed during the building phase. The exception was:
ExitFailure 1