Personally I thought Yown was a work in progress and just _why dabbling with Io rather than a practical joke.

I think Yown got me more interested in playing with Io than anything else. However the Builder is limited (because everything gets converted to a html tag). There are more complete HTML builders for Io on github.

Bruce Tate also provides a nice example of a HTML builder in *Seven languages in 7 weeks". Below is my slightly amended version of it:

    Builder := Object clone
    Builder forward := method ( 
        write ("<", call message name, ">") 
        call message arguments foreach (arg, 
            content := self doMessage (arg);
            if (content type == "Sequence" or content type == "Number", write(content))
        )
        write ("</", call message name, ">")
    )

    Builder do (
        html (
            h1 ("header")
            div (
                p ("paragraph", b ("bold"), "more text")
                ul (list(1,2,3) foreach (n, li (n)))
            )
        )
    )