diff options
Diffstat (limited to 'compiler/utils')
| -rw-r--r-- | compiler/utils/Util.hs | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/compiler/utils/Util.hs b/compiler/utils/Util.hs index c348f79888..c6c5362112 100644 --- a/compiler/utils/Util.hs +++ b/compiler/utils/Util.hs @@ -16,7 +16,7 @@ module Util ( -- * General list processing zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal, - zipLazy, stretchZipWith, zipWithAndUnzip, + zipLazy, stretchZipWith, zipWithAndUnzip, zipAndUnzip, zipWithLazy, zipWith3Lazy, @@ -441,6 +441,15 @@ zipWithAndUnzip f (a:as) (b:bs) (r1:rs1, r2:rs2) zipWithAndUnzip _ _ _ = ([],[]) +-- | This has the effect of making the two lists have equal length by dropping +-- the tail of the longer one. +zipAndUnzip :: [a] -> [b] -> ([a],[b]) +zipAndUnzip (a:as) (b:bs) + = let (rs1, rs2) = zipAndUnzip as bs + in + (a:rs1, b:rs2) +zipAndUnzip _ _ = ([],[]) + mapAccumL2 :: (s1 -> s2 -> a -> (s1, s2, b)) -> s1 -> s2 -> [a] -> (s1, s2, [b]) mapAccumL2 f s1 s2 xs = (s1', s2', ys) where ((s1', s2'), ys) = mapAccumL (\(s1, s2) x -> case f s1 s2 x of |