Evaluates expression in the specified environment and returns its
value. Expression must be a valid Scheme expression represented
as data, and environment-specifier must be a value returned by one
of the three procedures described below. Implementations may extend
eval to allow non-expression programs (definitions) as the first
argument and to allow other values as environments, with the restriction
eval is not allowed to create new bindings in the
environments associated with
(eval '(* 7 3) (scheme-report-environment 5)) ⇒ 21 (let ((f (eval '(lambda (f x) (f x x)) (null-environment)))) (f + 10)) ⇒ 20
Version must be an exact non-negative integer n
corresponding to a version of one of the Revised^n Reports on
Scheme-report-environment returns a specifier for an
environment that contains the set of bindings specified in the
corresponding report that the implementation supports.
Null-environment returns a specifier for an environment that
contains only the (syntactic) bindings for all the syntactic keywords
defined in the given version of the report.
Not all versions may be available in all implementations at all times. However, an implementation that conforms to version n of the Revised^n Reports on Scheme must accept version n. An error is signalled if the specified version is not available.
The effect of assigning (through the use of
eval) a variable
bound in a
scheme-report-environment (for example
unspecified. Thus the environments specified by
scheme-report-environment may be immutable.
This optional procedure returns a specifier for the environment that contains implementation-defined bindings, typically a superset of those listed in the report. The intent is that this procedure will return the environment in which the implementation would evaluate expressions dynamically typed by the user.
Here are some more
(require 'eval) ⇒ #<unspecified> (define car 'volvo) ⇒ #<unspecified> car ⇒ volvo (eval 'car (interaction-environment)) ⇒ volvo (eval 'car (scheme-report-environment 5)) ⇒ #<primitive-procedure car> (eval '(eval 'car (interaction-environment)) (scheme-report-environment 5)) ⇒ volvo (eval '(eval '(set! car 'buick) (interaction-environment)) (scheme-report-environment 5)) ⇒ #<unspecified> car ⇒ buick (eval 'car (scheme-report-environment 5)) ⇒ #<primitive-procedure car> (eval '(eval 'car (interaction-environment)) (scheme-report-environment 5)) ⇒ buick