From: Siemen Baader <siemenbaader@...>
Date: 2009-11-15T17:58:08+09:00
Subject: Traversing the contents of a proc (for a DSL)

Hi List,

Is it possible to traverse and modify the statements inside a Proc
after it has been created?

I'm playing with a small DSL for HTML, which should look like this.

html {
  head { title {"Hello World"} }
  body {
    h1 { "hello"}
    p {
     "text body"
     "more text"
    }
  }
}

If it is possible to recursively traverse through the statements in
each block, I could join the lines together with the + operator, and
the implementation would be fairly easy - just recursive calls that
return text. But it does not look like this is possible...

An alternative would be to create a new object for each node in the
HTML (eg body or h1), and let each method call inside this node assign
its content to an array there. Less functional style and more
overhead, but doable. But this requires either that I catch the
creation of new strings (no idea if that is possible) for them to be
added to the node as well, or that I introduce a new method to create
strings.

Any comments highly appreciated!

cheers,
Siemen