F# how to do List.map in parallel

Question

What is the most lightweight, terse way to run the following code in parallel within the standard F# libs? Or failing that any widely used additional libs?

let newlist = oldlist |> List.map myComplexFunction

The best I could find was

let newlist = oldlist |> List.map (fun x -> async { return myComplexFunction x }
                      |> Async.Parallel 
                      |> Async.RunSynchronously
                      |> Array.toList

I don't like this because it's 4 lines long and constructs an array that I then have to make back into a list. If I were working with Arrays it would be simple, Array.parallel, but I want to keep that lovely Immutable list functional purity. I just can't believe there is no list alternative, but so far have been unable to find one. Any good suggestions?

Answer 1

Use the PSeq module:

open Microsoft.FSharp.Collections

let newlist = 
    oldlist 
    |> PSeq.map myComplexFunction
    |> PSeq.toList