2-4-2025 - Match & List

Cons constructor :: appends item to the beginning of a list, but does not modify the original list since all variables are immutable element::list (‘a → ‘a list → ‘a list)

(e1:t list @ e2:t list): t list (‘a list → ‘a list → ‘a list)

Match expression

(match e1: t with
	 p1 -> e2:t2
	|p2 -> e3:t2
	|...
	|px -> ex:t2):t2

A list is

• an element that points to another list
• an empty list

let rec add1 lst = match lst with
[] -> []
|element::rest -> (element + 1)::(add1 rest)

RECURSION!

let rec mult5mtx mtx = match mtx with
[] -> []
|row::rest -> (mult5row row)::(mult5mtx mtx)
 
let rec mult5row row = match row with
[] -> []
|element::rest -> (element * 5)::(mult5row rest)