Use ‘parser-combinators-0.4.0’

CHANGELOG.md

@@ -1,5 +1,24 @@
 ## Megaparsec 6.4.0
 
+* `Text.Megaparsec` now re-exports `Control.Monad.Combinators` instead of
+  `Control.Applicative.Combinators` from `parser-combinators` because the
+  monadic counterparts of the familiar combinators are more efficient and
+  not as leaky.
+
+  This may cause minor breakage in certain cases:
+
+  * You import `Control.Applicative` and in that case there will be a name
+    conflict between `Control.Applicative.many` and
+    `Control.Monad.Combinator.many` now (the same for `some`).
+
+  * You define a polymorphic helper in terms of combinator(s) from
+    `Control.Applicative.Combinators` and use `Applicative` or `Alternative`
+    constraint. In this case you'll have to adjust the constraint to be
+    `Monad` or `MonadPlus` respectively.
+
+  Also note that the new `Control.Monad.Combinators` module we re-export now
+  re-exports `empty` from `Control.Applicative`.
+
 * Fix the `atEnd` parser. It now does not produce hints, so when you use it,
   it won't contribute to the “expecting end of input” component of parse
   error.

Text/Megaparsec.hs

@@ -77,7 +77,7 @@ module Text.Megaparsec
     module Text.Megaparsec.Pos
   , module Text.Megaparsec.Error
   , module Text.Megaparsec.Stream
-  , module Control.Applicative.Combinators
+  , module Control.Monad.Combinators
     -- * Data types
   , State (..)
   , Parsec
@@ -118,9 +118,9 @@ module Text.Megaparsec
   , dbg )
 where
 
-import Control.Applicative.Combinators
 import Control.DeepSeq
 import Control.Monad
+import Control.Monad.Combinators
 import Control.Monad.Cont.Class
 import Control.Monad.Error.Class
 import Control.Monad.Identity

Text/Megaparsec/Perm.hs

@@ -29,7 +29,7 @@ where
 import Text.Megaparsec
 
 #if !MIN_VERSION_base(4,8,0)
-import Control.Applicative ((<$>), (<*>))
+import Control.Applicative
 #endif
 
 infixl 1 <||>, <|?>
@@ -61,10 +61,11 @@ data Branch s m a = forall b. Branch (PermParser s m (b -> a)) (m b)
 makePermParser :: MonadParsec e s m
   => PermParser s m a -- ^ Given permutation parser
   -> m a              -- ^ Normal parser built from it
-makePermParser (Perm def xs) = choice (fmap branch xs ++ empty)
-  where empty = case def of
-                  Nothing -> []
-                  Just x  -> [return x]
+makePermParser (Perm def xs) = choice (fmap branch xs ++ empty')
+  where empty' =
+          case def of
+            Nothing -> []
+            Just x  -> [return x]
         branch (Branch perm p) = flip ($) <$> p <*> makePermParser perm
 
 -- | The expression @f \<$$> p@ creates a fresh permutation parser

megaparsec.cabal

@@ -40,7 +40,7 @@ library
                     , containers   >= 0.5   && < 0.6
                     , deepseq      >= 1.3   && < 1.5
                     , mtl          >= 2.0   && < 3.0
-                    , parser-combinators >= 0.1 && < 1.0
+                    , parser-combinators >= 0.4 && < 1.0
                     , scientific   >= 0.3.1 && < 0.4
                     , text         >= 0.2   && < 1.3
                     , transformers >= 0.4   && < 0.6
@@ -75,6 +75,7 @@ test-suite tests
   else
     ghc-options:      -O2 -Wall
   other-modules:      Control.Applicative.CombinatorsSpec
+                    , Control.Monad.CombinatorsSpec
                     , Test.Hspec.Megaparsec
                     , Test.Hspec.Megaparsec.AdHoc
                     , Text.Megaparsec.Byte.LexerSpec

stack.yaml

@@ -1,3 +1,5 @@
 resolver: lts-10.0
 packages:
 - '.'
+extra-deps:
+- parser-combinators-0.4.0