Aplikacje F#

//Projekt F#, nowy skrypt .fsx
open System

let x = 1
let inline add x y = x + y
let s1 = add 1 1
let s2 = add 1.0 1.0

//typ anonimowy
let tuple = (1, 2)
let first, second = tuple
fst tuple

let rec factorial1 n =
    if n = 0 || n = 1 then 1
    else n * factorial1 (n-1)

let factorial2 n =
    let rec factorial' n =
        if n = 0 || n = 1 then 1
        else n * factorial' (n-1)
    factorial' n

let factorial3 n =
    let rec factorial' acc n =
        if n = 0 || n = 1 then acc
        else factorial' (acc * n) (n-1)
    factorial' 1 n

//mechanizm dekompozycji (pattern matching)
let factorial5 n =
    let rec factorial' acc n =
        match n with
        | 0 | 1 -> acc
        | n -> factorial' (acc * n) (n-1)
    factorial' 1 n

//Highter order-function
let reduce neutralValue mapFunction n =
    if n <= 0 then failwith "n negative!"
    let rec loop acc n =
        if n <= 0 then acc else loop (mapFunction acc n) (n-1)
    loop neutralValue n

let product' = reduce 1 (*)
let sum' n = reduce 0 (+)

//acc - akumulator - poprzednia zawartość

let list = [1..5]
let square = fun x -> x * x
//mapowanie
List.map square list
List.map (fun x -> x * x) list

//inny sposob zapisu
[1..5]
|> List.map square

let l1 = 1 :: list // bardzo wydajna, tania operacja
let l2 = list @ list

List.head list
List.tail list
List.isEmpty list
List.length list

let isPalindrome xs = xs = List.rev xs
isPalindrome ['i';'i']

let f (x:int) = x
//F# for C# developers - ksiazka

let x1 = 1
let mutable x2 = 2
x2 <- 4
x2


//bcl
let f1 x y z = x + y + z
let f2 (x, y) = x + y
let f3 = f1 1

let rec doubleEverySecondNumber xs =
    match xs with
    | [] -> []
    | x :: y :: ys -> x :: 2 * y :: doubleEverySecondNumber ys
    | x :: ys -> x :: doubleEverySecondNumber ys

type Expression =
    | Value of double
    | Add of Expression * Expression
    // gwiazdka oznacza tuple'a
    // sub, multiply, divide etc. ...

let rec eval expression =
    match expression with
    | Value value -> value
    | Add (expr1, expr2) -> (eval expr1) + (eval expr2)

eval (Value 10.0)
eval (Add ((Value 10.0), (Value 10.0)))