OCaml From Very Beginning

02_let.ml

let isvowel c =
  c = 'a' || c = 'e' || c = 'i' || c = 'o' || c = 'u';;


let isconsonant c = not (isvowel c);;


let rec factorial n =
  if n <= 0 then 1
  else n * factorial (n - 1);;


let rec sum n =
  if n = 1 then 1
  else n + sum (n - 1);;



let rec power x n =
  if n = 0 then x
  else x * power x (n - 1);;

03_pattern_matching.ml

let rec factorial n =
  match n with
    1 -> 1
  | _ -> n * factorial (n - 1);;
  
  
let isvowel c =
  match c with
    'a' | 'e' | 'i' | 'o' | 'u' -> true
  | _ -> false;;
  

let rec gcd a b =
  match b with
    0 -> a
  | _ -> gcd b (a mod b);;
  

04_lists.ml

let isnil l =
  match l with
    [] -> true
  | _ -> false;;


let rec length l =
  match l with
    [] -> 0
  | _ :: tail -> 1 + length tail;;


let rec sum l =
  match l with
    [] -> 0
  | head :: tail -> head + sum tail;;


let rec length_inner l n =
  match l with
    [] -> n
  | head :: tail -> length_inner tail (n + 1);;

let length l = length_inner l 0;;


let rec odd_elements l =
  match l with
    a::_::t -> a :: odd_elements t
  | _ -> l;;


let rec append a b =
  match a with
    [] -> b
  | h::t -> h :: append t b;;


let rec rev l =
  match l with
    [] -> []
  | h::t -> rev t @ [h];;


let rec take n l =
  if n = 0 then [] else
    match l with
      h::t -> h :: take (n - 1) t;;


let rec drop n l =
  if n = 0 then l else
    match l with
      h::t -> drop (n - 1) t;;