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4.4 Evaluation and Examples

The scribble/eval library provides utilities for evaluating code at document-build time and incorporating the results in the document, especially to show example uses of defined procedures and syntax.

(interaction datum ...)
(interaction #:eval eval-expr datum ...)
Like racketinput, except that the result for each input datum is shown on the next line. The result is determined by evaluating the quoted form of the datum using the evaluator produced by eval-expr, if provided.

The eval-expr must produce a sandbox evaluator via make-evaluator or make-module-evaluator with the sandbox-output and sandbox-error-output parameters set to 'string. If eval is not provided, an evaluator is created using make-base-eval. See also make-eval-factory.

Uses of code:comment and code:blank are stipped from each datum before evaluation.

If a datum has the form (eval:alts show-datum eval-datum), then show-datum is typeset, while eval-datum is evaluated.

(interaction-eval datum)
(interaction-eval #:eval eval-expr datum)
Like interaction, evaluates the quoted form of datum, but returns the empty string.

(interaction-eval-show datum)
(interaction-eval-show #:eval eval-expr datum)
Like interaction-eval, but produces an element representing the printed form of the evaluation result.

(racketblock+eval datum ...)
(racketblock+eval #:eval eval-expr datum ...)

(racketmod+eval name datum ...)
(racketmod+eval #:eval eval-expr name datum ...)

(def+int defn-datum expr-datum ...)
(def+int #:eval eval-expr defn-datum expr-datum ...)
Like interaction, except the defn-datum is typeset as for racketblock (i.e., no prompt) and a line of space is inserted before the expr-datums.

(defs+int (defn-datum ...) expr-datum ...)
(defs+int #:eval eval-expr (defn-datum ...) expr-datum ...)
Like def+int, but for multiple leading definitions.

(examples datum ...)
(examples #:eval eval-expr datum ...)
Like interaction, but with an “Examples:” label prefixed.

(defexamples datum ...)
(defexamples #:eval eval-expr datum ...)
Like examples, but each definition using define or define-struct among the datums is typeset without a prompt, and with line of space after it.

(make-base-eval)  (any/c . -> . any)
Creates an evaluator using (make-evaluator 'racket/base), setting sandbox parameters to disable limits, set the outputs to 'string, and not add extra security guards.

(make-base-eval-factory mod-paths)  (-> (any/c . -> . any))
  mod-paths : (listof module-path?)
Produces a function that is like make-base-eval, except that each module in mod-paths is attached to the evaluator’s namespace. The modules are loaded and instantiated once (when the returned make-base-eval-like function is called the first time) and then attached to each evaluator that is created.

(make-eval-factory mod-paths)  (-> (any/c . -> . any))
  mod-paths : (listof module-path?)
Like make-base-eval-factor, but each module in mod-paths is also required into the top-level environment for each generated evaluator.

(close-eval eval)  (one-of/c "")
  eval : (any/c . -> . any)
Shuts down an evaluator produced by make-base-eval. Use close-eval when garbage collection cannot otherwise reclaim an evaluator (e.g., because it is defined in a module body).

  ((any/c . -> . any) any/c boolean? . -> . any)
(scribble-eval-handler handler)  void?
  handler : ((any/c . -> . any) any/c boolean? . -> . any)
A parameter that serves as a hook for evaluation. The evaluator to use is supplied as the first argument to the parameter’s value, and the second argument is the form to evaluate. The last argument is #t if exceptions are being captured (to display exception results), #f otherwise.