path: root/src/Propellor/Types/Core.hs
diff options
authorJoey Hess2018-04-30 09:03:46 -0400
committerJoey Hess2018-04-30 09:03:46 -0400
commit14fe4c4d6b5a29be94ecfc0572e0f9a9a081e795 (patch)
tree38ad23b09bd21a8569568335a13bfde9c16e79c1 /src/Propellor/Types/Core.hs
parent96ea8e04251bc23dd27faf1f486a2a9f9c29ff98 (diff)
fix broken SemigroupMonoid transition <<loop>>
Turns out that with ghc 8.2.2, the instructions given on the page don't work. And the cppless variant that I had compiles, but into effectively mappend = mappend so it loops. The only way I can see to make it work without cpp is to use mappend = (Sem.<>) which is ugly and a land mine waiting to explode if someone changes it to a nicer mappend = (<>) with a newer version of ghc which will compile it and work ok, while breaking it with 8.2.2. Sigh. I posted to haskell-cafe about this.
Diffstat (limited to 'src/Propellor/Types/Core.hs')
1 files changed, 1 insertions, 1 deletions
diff --git a/src/Propellor/Types/Core.hs b/src/Propellor/Types/Core.hs
index cd3e09c5..88c749b3 100644
--- a/src/Propellor/Types/Core.hs
+++ b/src/Propellor/Types/Core.hs
@@ -62,7 +62,7 @@ instance Sem.Semigroup (Propellor Result) where
instance Monoid (Propellor Result) where
mempty = return NoChange
- mappend = (<>)
+ mappend = (Sem.<>)
-- | An action that Propellor runs at the end, after trying to satisfy all
-- properties. It's passed the combined Result of the entire Propellor run.