[commit: packages/deepseq] master: Add instance for IORef and MVar (7367507)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/deepseq

On branch  : master
Link       : http://git.haskell.org/packages/deepseq.git/commitdiff/7367507ea499a05bd8976f3bd694ac014d2b27d9

>---------------------------------------------------------------

commit 7367507ea499a05bd8976f3bd694ac014d2b27d9
Author: Eric Mertens <emertens at gmail.com>
Date:   Mon Oct 12 23:33:01 2015 -0700

    Add instance for IORef and MVar
    
    Advances #6


>---------------------------------------------------------------

7367507ea499a05bd8976f3bd694ac014d2b27d9
 Control/DeepSeq.hs | 15 ++++++++++++++-
 changelog.md       |  3 +++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Control/DeepSeq.hs b/Control/DeepSeq.hs
index bcd5efc..cec8207 100644
--- a/Control/DeepSeq.hs
+++ b/Control/DeepSeq.hs
@@ -61,7 +61,8 @@ module Control.DeepSeq (
   ) where
 
 import Control.Applicative
-import Control.Concurrent ( ThreadId )
+import Control.Concurrent ( ThreadId, MVar )
+import Data.IORef
 import Data.Int
 import Data.Word
 import Data.Ratio
@@ -412,6 +413,18 @@ instance NFData TyCon where
     rnf tycon = rnfTyCon tycon
 #endif
 
+-- | __NOTE__: Only strict in the reference and not the referenced value.
+--
+-- /Since: 1.4.2.0/
+instance NFData (IORef a) where
+  rnf !_ = ()
+
+-- | __NOTE__: Only strict in the reference and not the referenced value.
+--
+-- /Since: 1.4.2.0/
+instance NFData (MVar a) where
+  rnf !_ = ()
+
 ----------------------------------------------------------------------------
 -- GHC Specifics
 
diff --git a/changelog.md b/changelog.md
index a700165..794d5ee 100644
--- a/changelog.md
+++ b/changelog.md
@@ -5,6 +5,9 @@
   * Added instances for `Ptr` and `FunPtr`
     ([#10](https://github.com/haskell/deepseq/pull/10))
 
+  * Added instance for `IORef` and `MVar`
+    ([#6](https://github.com/haskell/deepseq/issues/6))
+
 ## 1.4.1.2  *Aug 2015*
 
   * Avoid the broken combination of GHC-7.2 with `array>=0.4`