gistfile1.fs

let GetUnionExpressions<'a> expression =
     
    let getVisitorExpressions expression =
        let unionVisitor = new UnionVisitor<'a>()
        unionVisitor.Visit(expression : Expression) |> ignore
        unionVisitor.Expressions

    let rec getUnionExpressions (expressions : seq<UnionVisitor<'a>.UnionExpression>) = 
        if expressions |> Seq.isEmpty then Seq.empty
        else expressions 
                |> Seq.collect (fun x -> x.Expression |> getVisitorExpressions |> getUnionExpressions)
                |> Seq.append expressions  

    expression |> getVisitorExpressions |> getUnionExpressions