Fix error with eval in query.rkt

Racket handles the initial environment a bit differently to MIT scheme.

mceval/query.rkt

@@ -18,6 +18,10 @@
 
 #lang sicp
 
+(#%require (only racket/base make-base-namespace))
+
+(define user-initial-environment (make-base-namespace))
+
 ;; Racket versions of stream procedures
 ;; NB lang sicp uses promises for delayed evaluation.  These can be forced
 ;; directly with force (no evaluation needed).
@@ -137,8 +141,7 @@
 ;;(put 'lisp-value 'qeval lisp-value)
 
 (define (execute exp)
-  (apply (eval (predicate exp))         ; NB: racket eval seems to
-                                        ; always take the user initial environment.
+  (apply (eval (predicate exp) user-initial-environment)
          (args exp)))
 
 (define (always-true ignore frame-stream) frame-stream)