CE.fs

module Map =
    let union (l : Map<'K, 'V>) (r : Map<'K, 'V>) =
        (l, r) ||> Map.fold (fun l k v -> Map.add k v l)

type Node = Node of Map<string, string> * list<Node>

type SubNodeBuilder(attributes : Map<string, string>) =
    member x.Zero() = []
    member x.Yield(node : Node) = [node]
    member x.Combine(l, r) = l @ r()
    member x.Delay f = f
    member x.Run f = Node(attributes, f())

type NodeBuilder() =
    member x.Zero() = Map.empty
    member x.Yield(name : string, value : string) = Map.ofList [name, value]
    member x.Combine(l, r) = Map.union l (r())
    member x.Delay f = f
    member x.Run f = SubNodeBuilder(f())
    
type LeafBuilder() =
    member x.Zero() = Map.empty
    member x.Yield(name : string, value : string) = Map.ofList [name, value]
    member x.Combine(l, r) = Map.union l (r())
    member x.Delay f = f
    member x.Run f = Node(f(), [])


let node = NodeBuilder()
let leaf = LeafBuilder()


let test =
    (node { "a", "somevalue" }) {
        leaf { "b", "foo" }
        leaf { "b", "foo" }
    }