diff options
Diffstat (limited to 'src/Environment.hs')
| -rw-r--r-- | src/Environment.hs | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/src/Environment.hs b/src/Environment.hs index c0dd723..eef1948 100644 --- a/src/Environment.hs +++ b/src/Environment.hs @@ -19,6 +19,7 @@ module Environment import Control.Monad (when) import Data.List (intercalate) import Data.List.Split (splitOn) +import Data.Maybe (fromJust, isJust) import System.IO.Error (catchIOError, isDoesNotExistError) import qualified Graphics.Win32.Window as WinAPI @@ -64,12 +65,12 @@ notifyEnvUpdate = allWindows = WinAPI.castUINTPtrToPtr 0xffff -query :: RegistryLocation -> Registry.ValueName -> IO Registry.ValueData +query :: RegistryLocation -> Registry.ValueName -> IO (Maybe Registry.ValueData) query env name = do keyHandle <- openRegistryKey env - catchIOError (Registry.getString keyHandle name) emptyIfDoesNotExist + catchIOError (Registry.getString keyHandle name >>= return . Just) emptyIfDoesNotExist where - emptyIfDoesNotExist e = if isDoesNotExistError e then return "" else ioError e + emptyIfDoesNotExist e = if isDoesNotExistError e then return Nothing else ioError e engrave :: RegistryLocation -> Registry.ValueName -> Registry.ValueData -> IO () engrave env name value = do @@ -81,8 +82,12 @@ engraveWithPrompt :: RegistryLocation -> Registry.ValueName -> Registry.ValueDat engraveWithPrompt env name value = do putStrLn $ "Saving variable '" ++ name ++ "' to '" ++ registryKeyPath env ++ "'..." oldValue <- query env name - putStrLn $ "\tOld value: " ++ oldValue - putStrLn $ "\tNew value: " ++ value + if (isJust oldValue) + then do + putStrLn $ "\tOld value: " ++ fromJust oldValue + putStrLn $ "\tNew value: " ++ value + else do + putStrLn $ "\tValue: " ++ value agreed <- Utils.promptToContinue when agreed $ engrave env name value |