Make some combinators more efficient

Text/Megaparsec/Combinator.hs

@@ -57,13 +57,11 @@ choice = asum
 -- | @count n p@ parses @n@ occurrences of @p@. If @n@ is smaller or
 -- equal to zero, the parser equals to @return []@. Returns a list of @n@
 -- values.
---
--- This parser is defined in terms of 'count'', like this:
---
--- > count n = count' n n
 
-count :: Alternative m => Int -> m a -> m [a]
+count :: Applicative m => Int -> m a -> m [a]
-count n = count' n n
+count n p
+  | n <= 0    = pure []
+  | otherwise = sequenceA (replicate n p)
 {-# INLINE count #-}
 
 -- | @count\' m n p@ parses from @m@ to @n@ occurrences of @p@. If @n@ is
@@ -108,7 +106,6 @@ endBy1 p sep = some (p <* sep)
 
 manyTill :: Alternative m => m a -> m end -> m [a]
 manyTill p end = ([] <$ end) <|> someTill p end
-{-# INLINE manyTill #-}
 
 -- | @someTill p end@ works similarly to @manyTill p end@, but @p@ should
 -- succeed at least once.
@@ -148,7 +145,6 @@ sepBy1 p sep = (:) <$> p <*> many (sep *> p)
 
 sepEndBy :: Alternative m => m a -> m sep -> m [a]
 sepEndBy p sep = sepEndBy1 p sep <|> pure []
-{-# INLINE sepEndBy #-}
 
 -- | @sepEndBy1 p sep@ parses /one/ or more occurrences of @p@,
 -- separated and optionally ended by @sep@. Returns a list of values

Text/Megaparsec/Error.hs

@@ -171,6 +171,7 @@ mergeError e1@(ParseError pos1 _) e2@(ParseError pos2 ms2) =
     LT -> e2
     EQ -> addErrorMessages ms2 e1
     GT -> e1
+{-# INLINE mergeError #-}
 
 -- | @showMessages ms@ transforms list of error messages @ms@ into
 -- their textual representation.

Text/Megaparsec/Prim.hs

@@ -91,6 +91,7 @@ longestMatch s1@(State _ pos1 _) s2@(State _ pos2 _) =
     LT -> s2
     EQ -> s2
     GT -> s1
+{-# INLINE longestMatch #-}
 
 -- | All information available after parsing. This includes consumption of
 -- input, success (with return value) or failure (with parse error), parser
@@ -383,9 +384,9 @@ pZero = ParsecT $ \s@(State _ pos _) _ _ _ eerr ->
 pPlus :: ParsecT s m a -> ParsecT s m a -> ParsecT s m a
 pPlus m n = ParsecT $ \s cok cerr eok eerr ->
   let meerr err ms =
-        let ncerr err' s' = cerr (err' <> err) (longestMatch ms s')
+        let ncerr err' s' = cerr (mergeError err' err) (longestMatch ms s')
             neok x s' hs  = eok x s' (toHints err <> hs)
-            neerr err' s' = eerr (err' <> err) (longestMatch ms s')
+            neerr err' s' = eerr (mergeError err' err) (longestMatch ms s')
         in unParser n s cok ncerr neok neerr
   in unParser m s cok cerr eok meerr
 {-# INLINE pPlus #-}