Initial data commit

Task/Find-common-directory-path/Haskell/find-common-directory-path-1.hs

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+import Data.List
+
+-- Return the common prefix of two lists.
+commonPrefix2 (x:xs) (y:ys) | x == y = x : commonPrefix2 xs ys
+commonPrefix2 _ _ = []
+
+-- Return the common prefix of zero or more lists.
+commonPrefix (xs:xss) = foldr commonPrefix2 xs xss
+commonPrefix _ = []
+
+-- Split a string into path components.
+splitPath = groupBy (\_ c -> c /= '/')
+
+-- Return the common prefix of zero or more paths.
+-- Note that '/' by itself is not considered a path component,
+-- so "/" and "/foo" are treated as having nothing in common.
+commonDirPath = concat . commonPrefix . map splitPath
+
+main = putStrLn $ commonDirPath [
+        "/home/user1/tmp/coverage/test",
+        "/home/user1/tmp/covert/operator",
+        "/home/user1/tmp/coven/members"
+       ]

Task/Find-common-directory-path/Haskell/find-common-directory-path-2.hs

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+import Data.List (transpose, intercalate)
+import Data.List.Split (splitOn)
+
+
+------------------ COMMON DIRECTORY PATH -----------------
+
+commonDirectoryPath :: [String] -> String
+commonDirectoryPath [] = []
+commonDirectoryPath xs =
+  intercalate "/" $
+  head <$> takeWhile ((all . (==) . head) <*> tail) $
+  transpose (splitOn "/" <$> xs)
+
+--------------------------- TEST -------------------------
+main :: IO ()
+main =
+  (putStrLn . commonDirectoryPath)
+    [ "/home/user1/tmp/coverage/test"
+    , "/home/user1/tmp/covert/operator"
+    , "/home/user1/tmp/coven/members"
+    ]