From 0a7d5fa12467b0823bee3d883f9cd5d5d6f99887 Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@github.com>
Date: Thu, 4 Aug 2016 19:17:58 -0400
Subject: [PATCH] Add a function to retrieve the head element of a non-empty
 record.

---
 src/Data/Record.hs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/Data/Record.hs b/src/Data/Record.hs
index 5a2665428..12f3d37bd 100644
--- a/src/Data/Record.hs
+++ b/src/Data/Record.hs
@@ -2,6 +2,7 @@
 module Data.Record
 ( Record(..)
 , (.:)
+, rhead
 , HasField(..)
 , maybeGetField
 , updateField
@@ -25,6 +26,11 @@ infixr 0 .:
 (.:) :: Typeable h => h -> Record t -> Record (h ': t)
 (.:) = RCons
 
+-- | Get the first element of a non-empty record.
+rhead :: Record (head ': tail) -> head
+rhead (RCons head _) = head
+
+
 -- | Return 'Just' a 'field', if it exists in a record. Otherwise, return 'Nothing'.
 maybeGetField :: Typeable field => Record fields -> Maybe field
 maybeGetField (RCons h t) = cast h <|> maybeGetField t