## 1.1 - Product ```Ocaml let rec product = function | [] -> 0 | x::t -> x * product t;; ``` ## 1.2 - Count ```Ocaml let rec count x n = if x = [] then 0 else let e::t = x in if e = x then 1 + count t n else count t n;; ``` ## 1.3 - Search ```Ocaml let rec search x n = if x = [] then 0 else let e::t = x in if e = x then true else search t n;; ``` ## 1.4 - $n^{th}$ ```Ocaml let rec length l = if l = [] then 0 else let e::t = l in 1 + length t;; let rec nth x n = if (x = [] || n =< 0) then Invalid_arg "The number of element in the list is 0" else if length x < n then Failwith "The list is too short" else let e::t = x in if n = 0 return e else nth t (n-1) ;; ``` ## 1.5 - Maximum ```Ocaml let max l = if l = [] then 0 else let maxi = 0 let rec m = let e::t = l if e >= maxi then maxi = e else m t ```