Defined variables module, not fully working

lib/utility/utility.ml

@@ -40,6 +40,7 @@ let int_more_eq a b =
 let int_not a =
   if a > 0 then 0 else 1
 
+(* converts an integer to a list of chars such that it is pretty and linear *)
 let rec fromIntToString (alphabet: string) (x: int) : string =
   let base = String.length alphabet in
   if x < 0 then
@@ -47,4 +48,108 @@ let rec fromIntToString (alphabet: string) (x: int) : string =
   else if x < base then
     String.get alphabet x |> String.make 1
   else
-    (fromIntToString (alphabet) (x/base - 1)) ^ (String.get alphabet (x mod base) |> String.make 1)
+    (fromIntToString (alphabet) (x/base - 1)) ^ (String.get alphabet (x mod base)
+                                                 |> String.make 1)
+
+
+let inclusion la lb =
+  let rec aux la =
+    function
+      [] -> true
+    | b::lb ->
+      if List.mem b la
+      then aux la lb
+      else false
+  in
+  aux lb la
+
+let subtraction la lb =
+  let rec aux la =
+    function
+      [] -> la
+    | b::lb ->
+      aux (List.filter ((<>) b) la) lb
+  in
+  aux la lb
+
+(* returns only the unique elements of l *)
+let unique l =
+  let rec aux l acc =
+    match l with
+    | [] ->
+        List.rev acc
+    | h :: t ->
+      if List.mem h acc
+      then aux t acc
+      else aux t (h :: acc)
+  in
+  aux l []
+
+(* returns the unique elements of the concat of the lists *)
+let unique_union la lb =
+  unique (la @ lb)
+
+let unique_intersection la lb =
+  let rec aux la lb acc =
+    match la with
+      [] -> acc
+    | a::la ->
+      if List.mem a lb
+      then aux la lb (a::acc)
+      else aux la lb acc
+  in
+  aux la lb [] |> unique
+
+
+(* Complicated way to drop the last element and add a new option element to the
+   beginning *)
+let prev l a =
+  match l with
+  | [] ->
+    [a]
+  | _ ->
+    a :: (List.map (fun x -> Some x) (l |> List.rev |> List.tl |> List.rev))
+
+let pad l a n =
+  let l = List.map (fun i -> Some i) l in
+  if List.length l < n
+  then
+    l @ (List.init (n - List.length l) (fun _ -> a))
+  else
+    l
+
+let pad_opt l a n =
+  if List.length l < n
+  then
+    l @ (List.init (n - List.length l) (fun _ -> a))
+  else
+    l
+
+let combine la lb =
+  List.map2 (fun a b ->
+      match b with
+        None -> None
+      | Some b -> Some (a, b)
+    ) la lb
+
+let rec last_list l =
+  match l with
+    [] -> failwith "Utility.last_list, not enough items"
+  | [a] -> a
+  | _::ll -> last_list ll
+
+let add_to_last_list (la: 'a list list) (a: 'a) : 'a list list =
+  let rec aux la a =
+    match la with
+      [] -> [[a]]
+    | [l] -> [a :: l]
+    | l::la -> l :: (aux la a)
+  in
+  aux la a
+
+let rec combine_thrice la lb lc =
+  match (la, lb, lc) with
+  | [], [], [] -> []
+  | [a], [b], [c] -> [a, b, c]
+  | a::la, b::lb, c::lc -> (a, b, c) :: (combine_thrice la lb lc)
+  | _ -> []