What would a DSL for creating DSLs look like? And could it be self-hosted? It's turtles all the way down. :)
http://www.ccs.neu.edu/home/matthias/manifesto/sec_pl-pl.htm...
Kernel is like Scheme, except environments are first class objects which you can mutate and pass around. A typical use for such environment is for the second argument of $remote-eval, to limit the bindings available to the evaluator. If you treat an eDSL as a set of symbols representing it's vocabulary and grammar, then you bind them to a new environment with $bindings-environment, then passing a piece of code X to eval with this resulting argument as the second environment, will ensure X can only access those bindings (and built-in symbols which result from parsing Kernel, such as numbers), and nothing else.
There's a function make-kernel-standard-environment for easy self-hosting.
Trivial examples:
($define! x 1)
($remote-eval (+ x 2) (make-kernel-standard-environment))
> error: unbound symbol: x
($define! y 2)
($remote-eval (+ x y) (make-environment ($bindings->environment (x 1))
(make-kernel-standard-environment)))
> error: unbound symbol: y
($remote-eval (+ x y) ($bindings->environment (x 1) (y 2) (+ +)))
> 3
($define! x 1)
($define! y 2)
($remote-eval (+ x y) (get-current-environment))
> 3
($define! $remote-eval ($vau (o e) d (eval o (eval e d))))
And contrary to the opinions in the article, Kernel is the most expressively powerful language I know, and I'd recommend everyone learn it. You have a powerful but small and simple core language, from which you can derive your DSLs with as little or much power as you want them to have.
The ability to restrict the environment is key. Creating a DSL in standard Lisp would create a more powerful environment: the DSL would include all Lisp features plus the domain features.