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(slib.info)Eval

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Eval
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  `(require 'eval)'

 - Function: eval expression environment-specifier
     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 that `eval' is not allowed to create new bindings
     in the environments associated with `null-environment' or
     `scheme-report-environment'.

          (eval '(* 7 3) (scheme-report-environment 5))
                                                             =>  21
          
          (let ((f (eval '(lambda (f x) (f x x))
                         (null-environment))))
            (f + 10))
                                                             =>  20

 - Function: scheme-report-environment version
 - Function: null-environment version
 - Function: null-environment
     VERSION must be an exact non-negative integer N corresponding to a
     version of one of the Revised^N Reports on Scheme.
     `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 `car') is
     unspecified. Thus the environments specified by
     `scheme-report-environment' may be immutable.


 - Function: interaction-environment
     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 `eval' examples:

     (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