From 9d961e92e93f2f10b527fbbb2157cfc78e9e0cbe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Olivier=20Ch=C3=A9ron?= <olivier.cheron@gmail.com>
Date: Sat, 21 Apr 2018 07:55:25 +0200
Subject: [PATCH] Comment about not having Show instance for HMAC

Closes #232.
---
 Crypto/MAC/HMAC.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Crypto/MAC/HMAC.hs b/Crypto/MAC/HMAC.hs
index 77582e3..f44008a 100644
--- a/Crypto/MAC/HMAC.hs
+++ b/Crypto/MAC/HMAC.hs
@@ -32,7 +32,8 @@ import           Crypto.Internal.Imports
 
 -- | Represent an HMAC that is a phantom type with the hash used to produce the mac.
 --
--- The Eq instance is constant time.
+-- The Eq instance is constant time.  No Show instance is provided, to avoid
+-- printing by mistake.
 newtype HMAC a = HMAC { hmacGetDigest :: Digest a }
     deriving (ByteArrayAccess)