clean up read/show abuse

Avoid ever using read to parse a non-haskell formatted input string.

show :: Key is arguably still show abuse, but displaying Keys as filenames
is just too useful to give up.

Types/Crypto.hs

@@ -7,17 +7,9 @@
 
 module Types.Crypto where
 
-import Data.String.Utils
-
 -- XXX ideally, this would be a locked memory region
 newtype Cipher = Cipher String
 
 data EncryptedCipher = EncryptedCipher String KeyIds
 
 newtype KeyIds = KeyIds [String]
-
-instance Show KeyIds where
-	show (KeyIds ks) = join "," ks
-
-instance Read KeyIds where
-	readsPrec _ s = [(KeyIds (split "," s), "")]

Types/TrustLevel.hs

@@ -17,14 +17,4 @@ import Types.UUID
 data TrustLevel = SemiTrusted | UnTrusted | Trusted
 	deriving Eq
 
-instance Show TrustLevel where
-        show SemiTrusted = "?"
-        show UnTrusted = "0"
-        show Trusted = "1"
-
-instance Read TrustLevel where
-        readsPrec _ "1" = [(Trusted, "")]
-        readsPrec _ "0" = [(UnTrusted, "")]
-	readsPrec _ _ = [(SemiTrusted, "")]
-
 type TrustMap = M.Map UUID TrustLevel

Types/UUID.hs

@@ -9,13 +9,12 @@ module Types.UUID where
 
 -- A UUID is either an arbitrary opaque string, or UUID info may be missing.
 data UUID = NoUUID | UUID String
-	deriving (Eq, Ord)
+	deriving (Eq, Ord, Show)
 
-instance Show UUID where
-	show (UUID u) = u
-	show NoUUID = ""
+fromUUID :: UUID -> String
+fromUUID (UUID u) = u
+fromUUID NoUUID = ""
 
-instance Read UUID where
-	readsPrec _ s
-		| null s = [(NoUUID, "")]
-		| otherwise = [(UUID s, "")]
+toUUID :: String -> UUID
+toUUID [] = NoUUID
+toUUID s = UUID s