associativity for -> and <->

1 files changed, 5 insertions, 12 deletions

diff --git a/src/Parser.hs b/src/Parser.hs
index e328b6e..0891481 100644
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -79,16 +79,9 @@ pMultiMatOp s op = do
     Parsec.sepBy1
       pFormulaInner
       (Parsec.space *> Parsec.string s *> Parsec.space)
-  return $ foldl1 op (term : terms)
-
-pBinMatOp :: String -> (Formula -> Formula -> Formula) -> Parser Formula
-pBinMatOp s op = do
-  x <- pFormulaInner
-  _ <- Parsec.space
-  _ <- Parsec.string s
-  _ <- Parsec.space
-  y <- pFormulaInner
-  return $ op x y
+  -- Imp is right-associative, whereas And/Or/Iff can be either, so
+  -- use right-associative for everything.
+  return $ foldr1 op (term : terms)
 
 pNot :: Parser Formula
 pNot = Not <$> (Parsec.char '~' *> pFormulaInner)
@@ -115,8 +108,8 @@ pFormulaInner =
       (Parsec.char ')')
       ( Parsec.try (pMultiMatOp "&" And)
           <|> Parsec.try (pMultiMatOp "|" Or)
-          <|> Parsec.try (pBinMatOp "<->" Iff)
-          <|> Parsec.try (pBinMatOp "->" Imp)
+          <|> Parsec.try (pMultiMatOp "<->" Iff)
+          <|> Parsec.try (pMultiMatOp "->" Imp)
       )
     <|> Parsec.try pQuantifier