Tutorial

Here is an example of using the parallel sequence combinators:

#r "FSharp.Collections.ParallelSeq.dll"

open FSharp.Collections.ParallelSeq

let isPrime n =
    let upperBound = int (sqrt (float n))

    let hasDivisor =
        [ 2..upperBound ]
        |> List.exists (fun i -> n % i = 0)

    not hasDivisor

let nums = [| 1..500000 |]

let finalDigitOfPrimes =
    nums
    |> PSeq.filter isPrime
    |> PSeq.groupBy (fun i -> i % 10)
    |> PSeq.map (fun (k, vs) -> (k, Seq.length vs))
    |> PSeq.toArray

let averageOfFinalDigit =
    nums
    |> PSeq.filter isPrime
    |> PSeq.groupBy (fun i -> i % 10)
    |> PSeq.map (fun (k, vs) -> (k, Seq.length vs))
    |> PSeq.averageBy (fun (k, n) -> float n)

let sumOfLastDigitsOfPrimes =
    nums
    |> PSeq.filter isPrime
    |> PSeq.sumBy (fun x -> x % 10)