MIT/GNU Scheme, Cyclone: Does not follow dynamic scoping rule

[okuoku]

SRFI-34 and R7RS says:

That implicit cond expression is evaluated with the continuation and dynamic environment of the guard expression.

but MIT/GNU Scheme evaluates cond clauses inside body's dynamic environment, which is incorrect. Guile2 also affected but it is fixed in Guile3.

(define p0 (make-parameter 0))

(check-equal 'done4
             (parameterize
               ((p0 1))
               (check-equal 1 (p0))
               (guard
                 (cnd (#t
                       (check-equal 1 (p0)) ;; Guile2 and MIT/GNU Scheme says 2 here
                       'done4))
                 (check-equal 1 (p0))
                 (parameterize
                   ((p0 2))
                   (check-equal 2 (p0))
                   (raise 'bogus)))))

[okuoku]

Filed:

justinethier/cyclone#491

Tracked in exp2.