From 16fcfe1b2021e7da22028d85701f06615bd32326 Mon Sep 17 00:00:00 2001
From: David Ogborn <ogbornd@mcmaster.ca>
Date: Thu, 5 Dec 2019 11:57:17 -0500
Subject: [PATCH] added MonadPlus instance; fixed two warnings

---
 Language/Haskellish.hs | 10 ++++++++--
 haskellish.cabal       |  2 +-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/Language/Haskellish.hs b/Language/Haskellish.hs
index 43cf048..29dc14c 100644
--- a/Language/Haskellish.hs
+++ b/Language/Haskellish.hs
@@ -2,6 +2,7 @@ module Language.Haskellish where
 
 import Language.Haskell.Exts
 import Control.Applicative
+import Control.Monad
 import Data.Either (isRight)
 import Data.Maybe (catMaybes)
 
@@ -48,6 +49,10 @@ instance Monad Haskellish where
     runHaskellish (f x') e
     )
 
+instance MonadPlus Haskellish where
+  mzero = empty
+  mplus = (<|>)
+
 
 identifier :: Haskellish String -- note: we don't distinguish between identifiers and symbols
 identifier = Haskellish f
@@ -113,9 +118,9 @@ tuple p1 p2 = Haskellish (\e -> do
 asRightSection :: Haskellish (a -> b -> c) -> Haskellish b -> Haskellish (a -> c)
 asRightSection opP bP = Haskellish (\e -> do
   (opExp,bExp) <- f e
-  op <- runHaskellish opP opExp
+  op' <- runHaskellish opP opExp
   b <- runHaskellish bP bExp
-  return $ flip op b
+  return $ flip op' b
   )
   where
     f (Paren _ x) = f x
@@ -129,6 +134,7 @@ collectDoStatements (Do _ xs) = catMaybes $ fmap f xs
   where
     f (Qualifier _ e) = Just e
     f _ = Nothing
+collectDoStatements _ = []
 
 listOfDoStatements :: Haskellish a -> Haskellish [a]
 listOfDoStatements p = Haskellish (\e -> mapM (runHaskellish p) $ collectDoStatements e)
diff --git a/haskellish.cabal b/haskellish.cabal
index 20feee2..d4715f5 100644
--- a/haskellish.cabal
+++ b/haskellish.cabal
@@ -1,5 +1,5 @@
 name:                haskellish
-version:             0.1.0
+version:             0.1.1
 synopsis:            For parsing Haskell-ish languages
 homepage:            http://github.com/dktr0/Haskellish
 license:             BSD3