diff options
Diffstat (limited to 'compiler/GHC/Utils')
| -rw-r--r-- | compiler/GHC/Utils/Misc.hs | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/compiler/GHC/Utils/Misc.hs b/compiler/GHC/Utils/Misc.hs index af32a679bb..8dd60b5b64 100644 --- a/compiler/GHC/Utils/Misc.hs +++ b/compiler/GHC/Utils/Misc.hs @@ -27,7 +27,7 @@ module GHC.Utils.Misc ( dropWhileEndLE, spanEnd, last2, lastMaybe, onJust, - List.foldl1', foldl2, count, countWhile, all2, + List.foldl1', foldl2, count, countWhile, all2, all2Prefix, all3Prefix, lengthExceeds, lengthIs, lengthIsNot, lengthAtLeast, lengthAtMost, lengthLessThan, @@ -646,6 +646,25 @@ all2 _ [] [] = True all2 p (x:xs) (y:ys) = p x y && all2 p xs ys all2 _ _ _ = False +all2Prefix :: (a -> b -> Bool) -> [a] -> [b] -> Bool +-- ^ `all2Prefix p xs ys` is a fused version of `and $ zipWith2 p xs ys`. +-- So if one list is shorter than the other, `p` is assumed to be `True` for the +-- suffix. +all2Prefix p xs ys = go xs ys + where go (x:xs) (y:ys) = p x y && go xs ys + go _ _ = True +{-# INLINABLE all2Prefix #-} + +all3Prefix :: (a -> b -> c -> Bool) -> [a] -> [b] -> [c] -> Bool +-- ^ `all3Prefix p xs ys zs` is a fused version of `and $ zipWith3 p xs ys zs`. +-- So if one list is shorter than the others, `p` is assumed to be `True` for +-- the suffix. +all3Prefix p xs ys zs = go xs ys zs + where + go (x:xs) (y:ys) (z:zs) = p x y z && go xs ys zs + go _ _ _ = True +{-# INLINABLE all3Prefix #-} + -- Count the number of times a predicate is true count :: (a -> Bool) -> [a] -> Int |