Programación Funcional

Algunos ejemplo para empezar con este tipo de programación utilizando F#

open System 

[<EntryPoint>]

let main argv =
    System.IO.File.ReadLines("input.txt") |> Seq.map Int32.Parse |> Seq.sum |> printfn "%i"

    0 // return an integer exit code

---

open System

let isEven x = (x % 2) = 0

let rec result n = seq {
    if n<10 then n |> ignore
    else 
        if isEven (n%10) then yield (n%10)
        yield! result(n/10)
}


[<EntryPoint>]

let main argv = 
    System.IO.File.ReadLines("input.txt") |> Seq.map Int32.Parse |> Seq.item 0
    |> result |> Seq.rev |> printfn "%A"

    0 // return an integer exit code

---

open System

let count = 3
let myList = [1; 2; 3]
let myPriceList = [20; 10; 30]
let lengthList = myList |> List.sort

let priceList = myPriceList |> List.sort |> List.rev

let getIndex (n: int) = 
    List.findIndex(fun e -> e =  n) lengthList

let getPrice (n: int) =
    List.item n priceList

let rec iter items = 
  match items with
  | [] -> ()
  | head::tail -> 
     printf "%i " head
     getIndex head |> getPrice |> printfn "%i"
     iter tail

[<EntryPoint>]
let main argv =
    iter myList

    0 // return an integer exit code

---

open System

let count = 22
let myList= [5 ;6 ;4 ;135 ;4 ;210 ;135 ;135 ;5 ;4 ;4 ;135 ;4 ;6 ;6 ;135 ;6 ;5 ;5 ;4 ;5 ;6]
let resultList = List.distinct myList

let rec iter items = 
  match items with
  | [] -> ()
  | head::tail -> 
     printf "%i " head
     List.countBy(fun e -> if (e = head) then 1 else 0) myList 
     |> List.filter(fun (e,x) -> e = 1) |> List.item(0) |> snd |> printfn "%A"
     iter tail

[<EntryPoint>]
let main argv =
    iter resultList
    //for i in resultList do
    //    printf "%i " i
    //    List.countBy(fun e -> if (e = i) then 1 else 0) myList |> List.filter(fun (e,x) -> e = 1) |> List.item(0) |> snd |> printfn "%A"

    0 // return an integer exit code