funclang series3: Added assignment 7.

funclang-taddeus/series3/ass7.ml

+open List
+
+(* 1 *)
+let rec nth l n =
+    match n with
+    | 0 -> hd l
+    | i when i > 0 && i < (length l) -> nth (tl l) (i - 1)
+    | _ -> raise (Failure "list index out of bounds")
+;;
+
+(* 2 *)
+let heads l = map hd l;;
+
+(* 3 *)
+let zip l m =
+    let rec cut l e =
+        let len = (length l) in
+        if e = len then l else cut (rev (tl (rev l))) e
+    in
+    let min a b = if a > b then b else a in
+    let len = min (length l) (length m) in
+    List.combine (cut l len) (cut m len)
+;;
+
+(* 4 *)
+let rec map f l = if length l = 0 then [] else (f (hd l))::(map f (tl l));;
+
+(* 5 *)
+let rec reduce f z l =
+    match l with
+    | [] -> z
+    | h::t -> f z (reduce f h t)
+;;
+
+(* 6 *)
+let rec isSublist l s =
+    match s with
+    | [] -> true
+    | h::t -> h = (hd l) && isSublist (tl l) t
+;;
+
+(* 7 *)
+let rec lookup l key =
+    match l with
+    | [] -> raise (Failure "lookup")
+    | h::t -> let k, v = h in if k = key then v else lookup t key
+;;
+
+(* Challenge *)
+