I am still working on the implementation

of Chess in Scheme that I mentioned before.

For now, the most important part is to provide 

a language to describe rules of board games.

Until recently, the descriptions were all

pattern-based, which was a rather natural

approach, but it turned out that it was limited

too, because it didn't allow me to specify

e.g. that neither a king nor a rook was allowed

to move before castling, or that the captured

pawn's move must have been made in a previous

turn in case of the en-passent capture.

So I decided provide an environment where

some arbitrary Scheme code (specified in the

ruleset) could be executed, and where certain 

functions would reside that could be called

by that code.

And now I have a decision to make. One option

would be to create my own, restricted meta-circular

evaluator for a minimalistic subset of Scheme

(or use one that is already available). But I think

that it would be reinventing the wheel which is

already present in Guile Scheme, and is called

"eval" (or perhaps even "compile").

And hence my question: is there any way to restrict

the execution environment of eval, e.g. to specify

which symbols should be available? (For security

reasons, I wouldn't want functions like "system"

or "exit" to be present in that environment)

Or perhaps there's some better way to do that?

Regards,

M.