Fix Trac #3403: interaction of CPR and pattern-match failure

[ghc-hetmet.git] / compiler / parser / HaddockParse.y

diff --git a/compiler/parser/HaddockParse.y b/compiler/parser/HaddockParse.y
index e3f45f9..c0f64d4 100644 (file)
--- a/compiler/parser/HaddockParse.y
+++ b/compiler/parser/HaddockParse.y
@@ -1,5 +1,5 @@
 {
-{-# OPTIONS -w #-}
+{-# OPTIONS -Wwarn -w #-}
 -- The above warning supression flag is a temporary kludge.
 -- While working on this module you are encouraged to remove it and fix
 -- any warnings in the module. See
@@ -9,7 +9,7 @@
 module HaddockParse (
   parseHaddockParagraphs, 
   parseHaddockString, 
-  MyEither(..)
+  EitherString(..)
 ) where
 
 import {-# SOURCE #-} HaddockLex
@@ -17,6 +17,8 @@ import HsSyn
 import RdrName
 }
 
+%expect 0
+
 %tokentype { Token }
 
 %token '/'     { TokSpecial '/' }
@@ -35,7 +37,7 @@ import RdrName
        PARA    { TokPara }
        STRING  { TokString $$ }
 
-%monad { MyEither String }
+%monad { EitherString }
 
 %name parseHaddockParagraphs  doc
 %name parseHaddockString seq
@@ -98,15 +100,18 @@ strings  :: { String }
        | STRING strings        { $1 ++ $2 }
 
 {
-happyError :: [Token] -> MyEither String a
+happyError :: [Token] -> EitherString a
 happyError toks = MyLeft ("parse error in doc string")
 
 -- We don't want to make an instance for Either String,
 -- since every user of the GHC API would get that instance
 
-data MyEither a b = MyLeft a | MyRight b
+-- But why use non-Haskell98 instances when MyEither String
+-- is the only MyEither we're intending to use anyway? --Isaac Dupree
+--data MyEither a b = MyLeft a | MyRight b
+data EitherString b = MyLeft String | MyRight b
 
-instance Monad (MyEither String) where
+instance Monad EitherString where
        return          = MyRight
        MyLeft  l >>= _ = MyLeft l
        MyRight r >>= k = k r