    module System.LookupEnv (lookupEnv) where

    import System.Environment (getEnvironment)

    lookupEnv :: String -> IO (Maybe String)
    lookupEnv :: String -> IO (Maybe String)
    lookupEnv String
    envVar = ([(String, String)] -> Maybe String)
    -> IO [(String, String)] -> IO (Maybe String)
    forall a b. (a -> b) -> IO a -> IO b
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap (String -> [(String, String)] -> Maybe String
    forall a b. Eq a => a -> [(a, b)] -> Maybe b
    lookup String
    envVar) (IO [(String, String)] -> IO (Maybe String))
    -> IO [(String, String)] -> IO (Maybe String)
    forall a b. (a -> b) -> a -> b
    $ IO [(String, String)]
    getEnvironment