FSharp Html Templating

template.fs

namespace FSharpTemplate
  module Template = 
    type HtmlElement = 
      | Html of HtmlElement list
      | Head of HtmlElement list
      | Title of string

      | Body of HtmlElement list
      (* id, class, children *)
      | Div of string * string * HtmlElement list
      (* id, class, free-content, children *)
      | Para of string * string * string * HtmlElement list


    let layout (content:HtmlElement list) = 
      Html(
        [
          Head(
            [
              Title("F# Template!")
            ]
          ); 
          Body(content)
        ]
      )

    let new_doc = 
      layout [
                Div("main_div", "", 
                  [
                    Para("", "", "Some body content", [])
                  ]
                )
              ]

    let new_doc_with_text text =
      layout [
                Div("main_div", "", 
                  [
                    Para("", "", text, [])
                  ]
                )
              ]


    let document_text (document:HtmlElement) = 
      let join_words (l:string) r = l + r

      let rec node_text (element:HtmlElement) = 
        let node_name_and_children name children = 
          "<" + name + ">" + 
          (List.fold join_words "" (List.map node_text children)) + 
          "</" + name + ">"

        match element with
          | Html children -> "<!DOCTYPE>" + node_name_and_children "html" children
          | Head children -> node_name_and_children "head" children
          | Title t -> "<title>" + t + "</title>"
          | Body children -> node_name_and_children "body" children
          | Div (id, classname, children) ->
              "<div" +
              (if id.Length > 0 then " id=\"" + id + "\"" else "") +
              (if classname.Length > 0 then " classname=\"" + classname + "\"" else "") + 
              ">" + 
              (List.fold join_words "" (List.map node_text children)) + 
              "</div>"
          | Para (id, classname, free_content, children) ->
              "<p" + 
              (if id.Length > 0 then " id=\"" + id + "\"" else "") +
              (if classname.Length > 0 then " classname=\"" + classname + "\"" else "") + 
              ">" +
              (if free_content.Length > 0 then free_content else "") +
              (List.fold join_words "" (List.map node_text children)) + 
              "</p>"

      node_text document

    [<EntryPoint>]
    let main args = 
      let doc = if args.Length > 0 then
                  document_text (new_doc_with_text args.[0])
                else
                  document_text new_doc
        
      printfn "%s" doc

      (* Return 0 for success *)
      0