FuncProgSTHLM challenge

TailRecursiveSolution.fsx

//Challenge https://groups.google.com/group/functional-programming-sthlm/browse_thread/thread/647165dc2d923529?hl=sv
// The record type Part
type Part = {
    Heading : string;
    Text : string;
    IsColumnLayout : bool;
}

// Make some test data
let r = { Heading="Wide part"; Text="This is a wide part"; IsColumnLayout=false }
let g = { Heading="Column part"; Text="This is a column"; IsColumnLayout=true }

// A test list
let rnd = new System.Random()
let parts = [for x in 0..99999 -> rnd.Next(0, 2) |> fun v -> if v = 0 then r else g]

// The actual function, using pattern matching
let mapParts l = 
    let rec mapParts' l newl =
        match l with
        | p :: r :: tail when p.IsColumnLayout && r.IsColumnLayout -> let newl = (p, Some(r))::newl
                                                                      mapParts' tail newl
        | p :: tail -> let newl = (p, None)::newl 
                       mapParts' tail newl
        | [] -> List.rev(newl)
    mapParts' l []
    

//Test it
parts |> mapParts |> Seq.iter (printf "%A\r\n___\r\n")