example of immutable list in F#

list.fsx

let a = new obj();
let b = new obj();
let c = new obj();

a.Equals(b) // <- false
b.Equals(c) // <- false
c.Equals(a) // <- false

let aList = [a] // <- [System.Object]
let bList = [b] // <- [System.Object]
let cList = [c] // <- [System.Object]

let abList = aList @ bList // <- [System.Object; System.Object]

abList.Head.Equals(a)      // <- true
abList.Tail.Head.Equals(b) // <- true

let abcList = abList @ cList     // <- [System.Object; System.Object; System.Object]
abcList.Head.Equals(a)           // <- true
abcList.Tail.Head.Equals(b)      // <- true
abcList.Tail.Tail.Head.Equals(c) // <- true