From 6c8b7101fbe74055e19b1d9eec53597aa5b96b69 Mon Sep 17 00:00:00 2001
From: konsumlamm <konsumlamm@gmail.com>
Date: Mon, 20 Apr 2026 15:20:19 +0200
Subject: [PATCH] Fail on zero denominator in `Binary (Ratio a)` instance

---
 src/Data/Binary/Class.hs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Data/Binary/Class.hs b/src/Data/Binary/Class.hs
index 1efbe37..1cd5016 100644
--- a/src/Data/Binary/Class.hs
+++ b/src/Data/Binary/Class.hs
@@ -491,7 +491,10 @@ freezeByteArray arr = IO $ \s ->
 
 instance (Binary a,Integral a) => Binary (R.Ratio a) where
     put r = put (R.numerator r) <> put (R.denominator r)
-    get = liftM2 (R.%) get get
+    get = do
+        n <- get
+        d <- get
+        if d == 0 then fail "zero denominator" else pure (n R.% d)
 
 instance Binary a => Binary (Complex a) where
     {-# INLINE put #-}