Map Parts to groupings based on column/wide layout using F#

// 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 parts = [r; r; g; g; g; r; g]

let b = true
let c = not b

// The actual function, using pattern matching
let rec mapParts = function
    | p :: r :: tail when p.IsColumnLayout && r.IsColumnLayout -> (p, Some(r)) :: mapParts tail
    | p :: tail -> (p, None) :: mapParts tail
    | _ -> []

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