restructure + lecutre 07

lectures/02/notes02.ml

@@ -0,0 +1,135 @@
+(*
+  ***** TUPLES *****
+  has a fixed number of elements
+*)
+let x = (1, 2.1, "hello");;
+
+(*
+  this is also a tuple, but this tuple
+  is a different type to the tuple above
+*)
+let y = (1, 2.1, "hello", "goodbye");;
+
+(*
+  function with tuple argument
+
+  accepts a tuple with 3 elements of int
+*)
+let add_tuple (x, y, z) = x + y + z;;
+
+(*
+  ***** PATTERN MATCHING *****
+  where x gets deconstructed into a, b, and c
+*)
+let (a, b, c) = x;;
+
+a;;
+b;;
+c;;
+
+(*
+  ***** LISTS *****
+
+  lists are semi-colon seperated values of the same type
+  lists are a recursive data type
+*)
+let nums = [1; 2; 3];; (* this is a valid list *)
+
+(*
+  warning -
+  this is valid syntax but this is a list with a single
+  element that is a tuple of 3 ints
+*)
+let nums = [1, 2, 3];;
+(* results in - list : [(1, 2, 3)] *)
+
+(*
+  since lists are recursive data structures
+  we can add elements to the front of the list
+  as seen below
+
+  this operation is called cons
+*)
+2 :: (1 :: []);;
+2 :: 1 :: [];;
+
+(*
+  [1; 2; 3] === 1 :: 2 :: 3 :: [];;
+*)
+
+(* list of lists *)
+[[1; 2]; [3; 4]];;
+
+(* list concatonation *)
+[1; 2] @ [3; 4];;
+
+[];;
+(*
+  results in - : 'a list = []
+
+  where 'a means its a type variable
+  since lists are generic
+*)
+
+let l = [[1; 2]; [3]; []];;
+
+(*
+  pattern matching lists to extract 3
+  pattern matching must be exhaustive
+*)
+let [_; [x]; _] = l;;
+
+let data = [(1, 2, 'a'); (5, 3, 'b'); (4, 1, 'c'); (5, 0, 'd')];;
+let _ :: (_, _, x) :: _ = data;;
+x;;
+
+(*
+  recursive function
+  with pattern matching to find
+  length of list
+*)
+
+(**
+  * {length l} returns the number of elements
+  * in the list {l} - non tail recursive
+  *)
+let rec length l =
+  match l with
+  | [] -> 0
+  | x :: xs -> 1 + length xs;;
+
+(**
+  * {length_tr l} returns the number of elements
+  * in the list {l} - tail recursive
+  *)
+let length_tr l =
+  let rec aux acc l =
+    match l with
+    | [] -> acc
+    | _ :: xs -> aux (acc + 1) xs
+  in
+  aux 0 l;;
+
+(*
+  GENERATE WEB DOCUMENTATION
+
+  mkdir html
+  ocamldoc -html -d html main.ml
+
+*)
+
+(*
+  there is no void in ocaml,
+  everything has to return a value
+  all expressions have a value;
+
+  if your function has no value to
+  return, you still need to return something
+  so return the unit value
+
+  example:
+  printf is like a utility to print to the
+  console but does not need to return any value
+  so it returns the unit value
+*)
+Printf.printf "Hello, world\n";;