#2528: reverse the order of args to (==) in nubBy to match nub

This only makes a difference when the (==) definition is not
reflexive, but strictly speaking it does violate the report definition
of nubBy, so we should fix it.

diff --git a/Data/List.hs b/Data/List.hs
index af6b3f5..aca5cac 100644 (file)
--- a/Data/List.hs
+++ b/Data/List.hs
@@ -342,7 +342,7 @@ nubBy eq l              = nubBy' l []
 -- 'y' is the potential new element
 elem_by :: (a -> a -> Bool) -> a -> [a] -> Bool
 elem_by _  _ []         =  False
-elem_by eq y (x:xs)     =  x `eq` y || elem_by eq y xs
+elem_by eq y (x:xs)     =  y `eq` x || elem_by eq y xs
 #endif