alpha-rename the type signatures of foldl, foldl', and scanl to be consistent with foldr and scanr

libraries/base/Data/Foldable.hs

@@ -132,14 +132,14 @@ class Foldable t where
     -- | Left-associative fold of a structure.
     --
     -- @'foldl' f z = 'Prelude.foldl' f z . 'toList'@
-    foldl :: (a -> b -> a) -> a -> t b -> a
+    foldl :: (b -> a -> b) -> b -> t a -> b
     foldl f z t = appEndo (getDual (foldMap (Dual . Endo . flip f) t)) z
 
     -- | Left-associative fold of a structure.
     -- but with strict application of the operator.
     --
     -- @'foldl' f z = 'List.foldl'' f z . 'toList'@
-    foldl' :: (a -> b -> a) -> a -> t b -> a
+    foldl' :: (b -> a -> b) -> b -> t a -> b
     foldl' f z0 xs = foldr f' id xs z0
       where f' x k z = k $! f z x
 

libraries/base/Data/List.hs

@@ -45,8 +45,8 @@ module Data.List
 
    -- * Reducing lists (folds)
 
-   , foldl             -- :: (a -> b -> a) -> a -> [b] -> a
-   , foldl'            -- :: (a -> b -> a) -> a -> [b] -> a
+   , foldl             -- :: (b -> a -> b) -> b -> [a] -> b
+   , foldl'            -- :: (b -> a -> b) -> b -> [a] -> b
    , foldl1            -- :: (a -> a -> a) -> [a] -> a
    , foldl1'           -- :: (a -> a -> a) -> [a] -> a
    , foldr             -- :: (a -> b -> b) -> b -> [a] -> b
@@ -68,7 +68,7 @@ module Data.List
    -- * Building lists
 
    -- ** Scans
-   , scanl             -- :: (a -> b -> a) -> a -> [b] -> [a]
+   , scanl             -- :: (b -> a -> b) -> b -> [a] -> [b]
    , scanl1            -- :: (a -> a -> a) -> [a] -> [a]
    , scanr             -- :: (a -> b -> b) -> b -> [a] -> [b]
    , scanr1            -- :: (a -> a -> a) -> [a] -> [a]
@@ -1004,7 +1004,7 @@ unfoldr f b  =
 -- -----------------------------------------------------------------------------
 
 -- | A strict version of 'foldl'.
-foldl'           :: (a -> b -> a) -> a -> [b] -> a
+foldl'           :: (b -> a -> b) -> b -> [a] -> b
 #ifdef __GLASGOW_HASKELL__
 foldl' f z0 xs0 = lgo z0 xs0
     where lgo z []     = z

libraries/base/GHC/List.lhs

@@ -166,7 +166,7 @@ filterFB c p x r | p x       = x `c` r
 -- can be inlined, and then (often) strictness-analysed,
 -- and hence the classic space leak on foldl (+) 0 xs
 
-foldl        :: (a -> b -> a) -> a -> [b] -> a
+foldl        :: (b -> a -> b) -> b -> [a] -> b
 foldl f z0 xs0 = lgo z0 xs0
              where
                 lgo z []     =  z
@@ -181,7 +181,7 @@ foldl f z0 xs0 = lgo z0 xs0
 --
 -- > last (scanl f z xs) == foldl f z xs.
 
-scanl                   :: (a -> b -> a) -> a -> [b] -> [a]
+scanl                   :: (b -> a -> b) -> b -> [a] -> [b]
 scanl f q ls            =  q : (case ls of
                                 []   -> []
                                 x:xs -> scanl f (f q x) xs)