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-rw-r--r--haddock-api/src/Haddock/Syb.hs8
1 files changed, 7 insertions, 1 deletions
diff --git a/haddock-api/src/Haddock/Syb.hs b/haddock-api/src/Haddock/Syb.hs
index dd7ffc1b..3cec724e 100644
--- a/haddock-api/src/Haddock/Syb.hs
+++ b/haddock-api/src/Haddock/Syb.hs
@@ -2,7 +2,7 @@
module Haddock.Syb
- ( everything
+ ( everything, everywhere
, combine
) where
@@ -19,6 +19,12 @@ everything :: (r -> r -> r) -> (forall a. Data a => a -> r)
-> (forall a. Data a => a -> r)
everything k f x = foldl k (f x) (gmapQ (everything k f) x)
+-- | Apply transformation on each level of a tree.
+--
+-- Just like 'everything', this is stolen from SYB package.
+everywhere :: (forall a. Data a => a -> a) -> (forall a. Data a => a -> a)
+everywhere f = f . gmapT (everywhere f)
+
-- | Combine two queries into one using alternative combinator.
combine :: Alternative f => (forall a. Data a => a -> f r)
-> (forall a. Data a => a -> f r)