refactor(lib): Extract Errors into its own module

gibberish.cabal

@@ -97,6 +97,7 @@ library
     Data.Elocrypt,
     Data.Elocrypt.Trigraph,
     Data.Elocrypt.Utils,
+    Data.Gibberish.Errors,
     Data.Gibberish.Format,
     Data.Gibberish.MonadPass,
     Data.Gibberish.Trigraph,

src/Data/Gibberish/Errors.hs

@@ -0,0 +1,28 @@
+module Data.Gibberish.Errors
+  ( GibberishErr (..),
+    isTrigraphNotFound,
+    isImpossibleError,
+  ) where
+
+import Control.Exception (Exception ())
+import Data.Typeable (Typeable ())
+
+-- | Exceptions that can occur at runtime
+data GibberishErr
+  = TrigraphNotFound FilePath
+  | ImpossibleError
+  deriving stock (Eq, Typeable)
+
+instance Exception GibberishErr
+
+instance Show GibberishErr where
+  show (TrigraphNotFound path) = "Trigraph file " <> show path <> " does not exist!"
+  show ImpossibleError = "The impossible happened! Please file a bug report."
+
+isTrigraphNotFound :: GibberishErr -> Bool
+isTrigraphNotFound (TrigraphNotFound _) = True
+isTrigraphNotFound _ = False
+
+isImpossibleError :: GibberishErr -> Bool
+isImpossibleError ImpossibleError = True
+isImpossibleError _ = False

src/Data/Gibberish/Types.hs

@@ -2,24 +2,24 @@
 
 module Data.Gibberish.Types
   ( GenPassOptions (..),
-    Error (..),
     Unigram (..),
     Digram (..),
     Trigram (..),
     Frequency (..),
     Frequencies (..),
     Trigraph (..),
     Word (..),
+    module Data.Gibberish.Errors,
   ) where
 
+import Data.Gibberish.Errors
+
 import Control.DeepSeq (NFData)
-import Control.Exception (Exception ())
 import Data.Aeson (FromJSON (..), FromJSONKey (..), ToJSON (..), ToJSONKey (..))
 import Data.Aeson qualified as Aeson
 import Data.Aeson.Types (FromJSONKeyFunction (..), Parser (), toJSONKeyText)
 import Data.Map (Map ())
 import Data.Text (Text ())
-import Data.Typeable (Typeable ())
 import GHC.Generics (Generic ())
 import TextShow (TextShow (..), fromString)
 import Prelude hiding (Word ())
@@ -37,12 +37,6 @@ data GenPassOptions = GenPassOptions
   }
   deriving stock (Eq, Show)
 
--- | Exceptions that can occur at runtime
-data Error
-  = TrigraphNotFound FilePath
-  | ImpossibleError
-  deriving stock (Eq, Typeable)
-
 -- | A unigram is a single letter
 newtype Unigram = Unigram {unUnigram :: Char}
   deriving stock (Eq, Ord, Show)
@@ -79,12 +73,6 @@ newtype Trigraph = Trigraph {unTrigraph :: Map Digram Frequencies}
 newtype Word = Word {unWord :: Text}
   deriving stock (Eq, Show)
 
-instance Exception Error
-
-instance Show Error where
-  show (TrigraphNotFound path) = "Trigraph file " <> show path <> " does not exist!"
-  show ImpossibleError = "The impossible happened! Please file a bug report."
-
 instance TextShow Digram where
   showb (Digram c1 c2) = fromString [c1, c2]
 

test/Data/Gibberish/TrigraphSpec.hs

@@ -70,7 +70,7 @@ spec = do
 
     it "handles load failure" $ do
       loadTrigraph (CustomTrigraph $ TrigraphConfig "doesnotexist.json")
-        `shouldThrow` (== TrigraphNotFound "doesnotexist.json")
+        `shouldThrow` isTrigraphNotFound
 
 trigrams :: Text -> [Trigram]
 trigrams ts = case Text.take 3 ts of