Path: utzoo!attcan!uunet!jarthur!elroy.jpl.nasa.gov!decwrl!shelby!neon!news
From: rit@killdeer.stanford.edu (Jean-Francois Rit)
Newsgroups: comp.lang.lisp
Subject: retarded evaluation question
Message-ID: <1990Mar16.170540.20445@Neon.Stanford.EDU>
Date: 16 Mar 90 17:05:40 GMT
References: <1004@micropen> <8218@hubcap.clemson.edu> <1819@awdprime.UUCP>
Sender: news@Neon.Stanford.EDU (USENET News System)
Reply-To: rit@killdeer.stanford.edu (Jean-Francois Rit)
Organization: Robotics Lab. Stanford University
Lines: 15

What is an elegant solution to implement the following function:

(defxxx with-bindings (b-list s-exprs)
 "evaluates the s-exprs in an implicit progn. If the argument s-exprs contains
 free variables, they are bound according to b-list. 
 Example: (setq sub '((?x (1 2)) (?y (3 5)))
                clause '(+ (car ?x) (cadr ?y))) 
          --> (+ (car ?x) (cadr ?y))
          (with-bindings sub clause)
          --> 6")

Note that a macro expanding to a let won't work, since sub, for instance, is a
symbol, not a cons.

JF Rit