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Diffstat (limited to 'compiler/utils/Util.hs')
| -rw-r--r-- | compiler/utils/Util.hs | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/compiler/utils/Util.hs b/compiler/utils/Util.hs index 7d44a5004b..aa3a19b64c 100644 --- a/compiler/utils/Util.hs +++ b/compiler/utils/Util.hs @@ -14,6 +14,8 @@ module Util ( zipEqual, zipWithEqual, zipWith3Equal, zipWith4Equal, zipLazy, stretchZipWith, zipWithAndUnzip, + filterByList, + unzipWith, mapFst, mapSnd, chkAppend, @@ -301,6 +303,15 @@ zipLazy :: [a] -> [b] -> [(a,b)] zipLazy [] _ = [] zipLazy (x:xs) ~(y:ys) = (x,y) : zipLazy xs ys +-- | 'filterByList' takes a list of Bools and a list of some elements and +-- filters out these elements for which the corresponding value in the list of +-- Bools is False. This function does not check whether the lists have equal +-- length. +filterByList :: [Bool] -> [a] -> [a] +filterByList (True:bs) (x:xs) = x : filterByList bs xs +filterByList (False:bs) (_:xs) = filterByList bs xs +filterByList _ _ = [] + stretchZipWith :: (a -> Bool) -> b -> (a->b->c) -> [a] -> [b] -> [c] -- ^ @stretchZipWith p z f xs ys@ stretches @ys@ by inserting @z@ in -- the places where @p@ returns @True@ |