[commit: pretty] ghc-7.4: Add note explaining why we use a different <> (f615a6a)

[Johan Tibell]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/pretty

On branch  : ghc-7.4

http://hackage.haskell.org/trac/ghc/changeset/f615a6aeb4abcdbfbfab67b0a82cef9a9a65ec49

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

commit f615a6aeb4abcdbfbfab67b0a82cef9a9a65ec49
Author: Johan Tibell <johan.tibell at gmail.com>
Date:   Wed Jan 4 10:06:50 2012 -0800

    Add note explaining why we use a different <>

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

 Text/PrettyPrint/HughesPJ.hs |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/Text/PrettyPrint/HughesPJ.hs b/Text/PrettyPrint/HughesPJ.hs
index 974eee7..96c4d13 100644
--- a/Text/PrettyPrint/HughesPJ.hs
+++ b/Text/PrettyPrint/HughesPJ.hs
@@ -543,6 +543,10 @@ nilAboveNest g k q           | not g && k > 0      -- No newline if no overlap
 -- ---------------------------------------------------------------------------
 -- Horizontal composition @<>@
 
+-- We intentionally avoid Data.Monoid.(<>) here due to interactions of
+-- Data.Monoid.(<>) and (<+>).  See
+-- http://www.haskell.org/pipermail/libraries/2011-November/017066.html
+
 -- | Beside.
 -- '<>' is associative, with identity 'empty'.
 (<>) :: Doc -> Doc -> Doc