module Data.ByteString.Extra where
import Control.Exception ( catch )
import qualified Data.ByteString.Lazy as B
import System.IO.Error ( isDoesNotExistError )
safeReadFile :: FilePath -> IO (Either String B.ByteString)
safeReadFile :: String -> IO (Either String ByteString)
safeReadFile String
fp =
IO (Either String ByteString)
-> (IOError -> IO (Either String ByteString))
-> IO (Either String ByteString)
forall e a. Exception e => IO a -> (e -> IO a) -> IO a
catch (ByteString -> Either String ByteString
forall a. a -> Either String a
forall (m :: * -> *) a. Monad m => a -> m a
return (ByteString -> Either String ByteString)
-> IO ByteString -> IO (Either String ByteString)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> String -> IO ByteString
B.readFile String
fp) ((IOError -> IO (Either String ByteString))
-> IO (Either String ByteString))
-> (IOError -> IO (Either String ByteString))
-> IO (Either String ByteString)
forall a b. (a -> b) -> a -> b
$ \IOError
e ->
if IOError -> Bool
isDoesNotExistError IOError
e
then Either String ByteString -> IO (Either String ByteString)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (Either String ByteString -> IO (Either String ByteString))
-> Either String ByteString -> IO (Either String ByteString)
forall a b. (a -> b) -> a -> b
$ String -> Either String ByteString
forall a b. a -> Either a b
Left (String -> Either String ByteString)
-> String -> Either String ByteString
forall a b. (a -> b) -> a -> b
$ String -> String
strByteStringFileNotFound String
fp
else Either String ByteString -> IO (Either String ByteString)
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return (Either String ByteString -> IO (Either String ByteString))
-> Either String ByteString -> IO (Either String ByteString)
forall a b. (a -> b) -> a -> b
$ String -> Either String ByteString
forall a b. a -> Either a b
Left (String -> Either String ByteString)
-> String -> Either String ByteString
forall a b. (a -> b) -> a -> b
$ String -> String
strByteStringCannotOpenFile String
fp
strByteStringFileNotFound :: FilePath -> String
strByteStringFileNotFound :: String -> String
strByteStringFileNotFound String
fp = String
"File not found: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
fp
strByteStringCannotOpenFile :: FilePath -> String
strByteStringCannotOpenFile :: String -> String
strByteStringCannotOpenFile String
fp = String
"Error opening file " String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
fp