Remove IsString instance of `Jid'

IsString instances are never supposed to fail, but parsing Strings to
JIDs might. We might do this later with Template Haskell instead, or
something.

source/Network/Xmpp/Marshal.hs

@@ -277,4 +277,4 @@ xpJid :: PU Text Jid
 xpJid = PU { unpickleTree = \input -> case jidFromText input of
                   Nothing -> UnpickleError $ ErrorMessage "Could not parse JID."
                   Just jid -> Result jid Nothing
-           , pickleTree = \input -> pack $ jidToText input }
+           , pickleTree = \input -> jidToText input }

source/Network/Xmpp/Types.hs

@@ -936,9 +936,6 @@ parseJid s = case jidFromText $ Text.pack s of
                  Just jid -> jid
                  Nothing -> error $ "Jid value (" ++ s ++ ") did not validate"
 
-instance IsString Jid where
-  fromString = fromJust . jidFromText . Text.pack
-
 -- | Converts a Text to a JID.
 jidFromText :: Text -> Maybe Jid
 jidFromText t = do

tests/Tests.hs

@@ -28,13 +28,13 @@ import           System.Environment
 import           System.Log.Logger
 
 testUser1 :: Jid
-testUser1 = "echo1@species64739.dyndns.org/bot"
+testUser1 = parseJid "echo1@species64739.dyndns.org/bot"
 
 testUser2 :: Jid
-testUser2 = "echo2@species64739.dyndns.org/bot"
+testUser2 = parseJid "echo2@species64739.dyndns.org/bot"
 
 supervisor :: Jid
-supervisor = "uart14@species64739.dyndns.org"
+supervisor = parseJid "uart14@species64739.dyndns.org"
 
 config = def{sessionStreamConfiguration
               = def{connectionDetails = UseHost "localhost" (PortNumber 5222)}}