get rid of eitherToParser

haskell/nfker7h/lib/Language/Yanais/Nfker7h/Parser/Lex.hs

@@ -7,6 +7,7 @@ module Language.Yanais.Nfker7h.Parser.Lex (
 
 -- import Debug.Trace
 
+import Control.Monad.Error.Class (MonadError(..))
 import Control.Monad.State.Strict
 import qualified Data.HashMap.Strict as H
 import Language.Yanais.Parser
@@ -49,17 +50,18 @@ handleIdentsI :: Parser' Error (Maybe TokenKind)
 handleIdentsI = do
   pfx <- eats lexeIdentPrefixTree
   marker <- gets peOffset
-  ident' <- takeIdent >>= (\ident -> eitherToParser $ case ident of
-    Left exc -> Left $ DteUnicodeExc exc
-    Right x -> Right x)
-  case tmp pfx ident' marker of
+  ident' <- takeIdent
+  ident <- case ident' of
+    Left exc -> throwError $ DteUnicodeExc exc
+    Right x -> pure x
+  case tmp pfx ident marker of
     Just x -> pure . Just $ x
     Nothing -> do
       gtc <- tryOne Just
       -- usually this is an error, but not at EOF
-      eitherToParser $ case gtc of
-        Just gtc_ -> Left $ UnexpectedChar marker gtc_
-        Nothing -> Right Nothing
+      case gtc of
+        Just gtc_ -> throwError $ UnexpectedChar marker gtc_
+        Nothing -> pure Nothing
 
   where
     tmp (Just IpDot) (Just x) _ = Just $ TDotIdent x

haskell/nfker7h/lib/Language/Yanais/Parser.hs

@@ -13,7 +13,6 @@ module Language.Yanais.Parser (
     Span(..),
     HandleTree(..),
     emptyIdent,
-    eitherToParser,
 
     -- creating and running parsers
     makeParseEnv,
@@ -97,12 +96,8 @@ instance MonadState s (Parser s e) where
     state = Parser . state
     {-# INLINE state #-}
 
--- | injects an `Either` into the parser (used to conditionally throw errors)
-eitherToParser :: Either e a -> Parser s e a
-eitherToParser e = Parser . StateT $ \st -> fmap (\x -> (x, st)) e
-
 instance MonadError e (Parser s e) where
-    throwError e = Parser . StateT $ \st -> Left e
+    throwError e = Parser . StateT . const $ Left e
     catchError (Parser (StateT m)) eh = Parser . StateT $ \st -> case m st of
       Left err -> let (Parser (StateT ehp)) = eh err in ehp st
       Right x -> Right x