all tasks

Task/Substring/Oz/substring.oz

@@ -0,0 +1,21 @@
+declare
+  fun {DropUntil Xs Prefix}
+     case Xs of nil then nil
+     [] _|Xr then
+        if {List.isPrefix Prefix Xs} then Xs
+        else {DropUntil Xr Prefix}
+        end
+     end
+  end
+
+  Digits = "1234567890"
+in
+  {ForAll
+   [{List.take {List.drop Digits 2} 3}     = "345"
+    {List.drop Digits 2}                   = "34567890"
+    {List.take Digits {Length Digits}-1}   = "123456789"
+    {List.take {DropUntil Digits "4"} 3}   = "456"
+    {List.take {DropUntil Digits "56"} 3}  = "567"
+    {List.take {DropUntil Digits "31"} 3}  = ""
+   ]
+   System.showInfo}