diff options
| -rw-r--r-- | docs/users_guide/glasgow_exts.xml | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml index 16cc760d2a..54b7a0f609 100644 --- a/docs/users_guide/glasgow_exts.xml +++ b/docs/users_guide/glasgow_exts.xml @@ -8416,7 +8416,11 @@ data T = T {-# UNPACK #-} !Float compiler).</para> <para>Unpacking constructor fields should only be used in - conjunction with <option>-O</option>, in order to expose + conjunction with <option>-O</option><footnote>in fact, UNPACK + has no effect without <option>-O</option>, for technical + reasons + (see <ulink url="http://hackage.haskell.org/trac/ghc/ticket/5252">tick + 5252</ulink>)</footnote>, in order to expose unfoldings to the compiler so the reboxing can be removed as often as possible. For example:</para> |