Initial data commit

Task/Find-common-directory-path/Standard-ML/find-common-directory-path.ml

@@ -0,0 +1,21 @@
+fun takeWhileEq ([], _) = []
+  | takeWhileEq (_, []) = []
+  | takeWhileEq (x :: xs, y :: ys) =
+      if x = y then x :: takeWhileEq (xs, ys) else []
+
+fun commonPath sep =
+  let
+    val commonInit = fn [] => [] | x :: xs => foldl takeWhileEq x xs
+    and split = String.fields (fn c => c = sep)
+    and join = String.concatWith (str sep)
+  in
+    join o commonInit o map split
+  end
+
+val paths = [
+  "/home/user1/tmp/coverage/test",
+  "/home/user1/tmp/covert/operator",
+  "/home/user1/tmp/coven/members"
+]
+
+val () = print (commonPath #"/" paths ^ "\n")