Best practices for processing s-expressions representing configurations/DSLs

[Stephen Scheck]

Hello,

I'm very new to Guile/Scheme/Lisp programming (but love the concise,
minimalist syntax!), so please bear with what may be some obvious answers.

When representing application configurations or DSLs as s-expressions, what
are common or best strategies for processing them? For example, here's an
excerpt I found of the Guix package definition DSL to study as a prototype:

    (package
      (name "hello")
      (version "2.10")
      (build-system gnu-build-system)
      (arguments '(#:configure-flags '("--enable-silent-rules")))
      (inputs `(("gawk" ,gawk)))
      (synopsis "Hello, GNU world: An example GNU package")
      (description "Guess what GNU Hello prints!")
      (home-page "http://www.gnu.org/software/hello/";)
      (license gpl3+))

Would this just be executed directly within the equivalent of a regular
Guile REPL (with the Guix extensions loaded, of course) ? Is each "key"
(e.g. "name" or "build-system") just a function call? Or would it be better
to slurp the whole s-expr in as a quoted, unevaluated structure, and
iterate through its various sub-components, using conditionals to match the
various keys and processing as necessary? I.e. would it be more typical to
view the structure as just data, an arbitrarily nested list structure, with
separate code to process it, or as code itself? Oh homoiconicity, it is a
slippery notion!