open System

// Unlike arrays, lists in F# are immutable and can have any length.
// An empty list is represented by []
let emptyList: string list = []
printfn "uninit: %A %b %b" emptyList (emptyList = []) (emptyList.Length = 0)

// To create a list with initial values, we can use the list literal syntax
let s = ["a"; "b"; "c"]
printfn "init: %A" s

// We can access elements using indexing
printfn "get: %s" s.[2]

// len returns the length of the list
printfn "len: %d" s.Length

// We can add elements to a list using the cons operator '::'
// or the '@' operator for concatenating lists
let s2 = s @ ["d"]
let s3 = s2 @ ["e"; "f"]
printfn "add: %A" s3

// Lists can be copied using the List.map function
let c = List.map id s3
printfn "copy: %A" c

// We can slice lists using the '[start..end]' syntax
let l1 = s3.[2..4]
printfn "sl1: %A" l1

// This slices up to (but excluding) index 5
let l2 = s3.[0..4]
printfn "sl2: %A" l2

// And this slices from index 2 to the end
let l3 = s3.[2..]
printfn "sl3: %A" l3

// We can declare and initialize a list in a single line
let t = ["g"; "h"; "i"]
printfn "dcl: %A" t

// F# provides many useful functions for working with lists
let t2 = ["g"; "h"; "i"]
if t = t2 then
    printfn "t = t2"

// Lists can be composed into multi-dimensional data structures
let twoD = 
    [for i in 0..2 -> 
        [for j in 0..i -> i + j]]
printfn "2d: %A" twoD