language-level@ : unit?

language-level^ : signature

(make-language-level   name       path       mixin ...      [ #:number number       #:hierarchy hierarchy       #:summary summary       #:url url       #:reader reader])

→ (is-a?/c drracket:language:language<%>)

name : string?

path : module-path?

mixin : (-> class? class?)

number : integer? = ...

hierarchy : (listof (cons/c string? integer?)) = ...

summary : string? = name

url : (or/c string? #f) = #f

reader   :   (->* [] [any/c input-port?] (or/c syntax? eof-object?))       =   read-syntax

Constructs a language level as an instance of drracket:language:language<%> with the given name based on the language defined by the module at path. Applies (drracket:language:get-default-mixin) and the given mixins to simple-language-level% to construct the class, and uses the optional keyword arguments to fill in the language’s description and reader.

simple-language-level%  :  (and/c (implementation?/c drracket:language:language<%>)        (implementation?/c drracket:language:module-based-language<%>)        (implementation?/c drracket:language:simple-module-based-language<%>))

Equal to (drracket:language:module-based-language->language-mixin (drracket:language:simple-module-based-language->module-based-language-mixin drracket:language:simple-module-based-language%)).

(language-level-render-mixin   to-sexp       show-void?)

→ (make-mixin-contract drracket:language:language<%>)

to-sexp : (-> any/c any/c)

show-void? : boolean?

Produces a mixin that overrides render-value/format to apply to-sexp to each value before printing it, and to skip void? values (pre-transformation) if show-void? is #f.

(language-level-capability-mixin dict)

→ (make-mixin-contract drracket:language:language<%>)

dict : dict?

Produces a mixin that augments capability-value to look up each key in dict, producing the corresponding value if the key is found and deferring to inner otherwise.

language-level-no-executable-mixin : (make-mixin-contract drracket:language:language<%>)

Overrides create-executable to print an error message in a dialog box.

language-level-eval-as-module-mixin  :  (make-mixin-contract drracket:language:language<%>                      drracket:language:module-based-language<%>)

Overrides front-end/complete-program to wrap terms from the definition in a module based on the language level’s definition module. This duplicates the behavior of the HtDP teaching languages, for instance.

language-level-macro-stepper-mixin : (make-mixin-contract drracket:language:language<%>)

This mixin enables the macro stepper for its language level.

language-level-check-expect-mixin : (make-mixin-contract drracket:language:language<%>)

This mixin overrides on-execute to set up the check-expect test engine to a language level similarly to the HtDP teaching languages.

(language-level-metadata-mixin   reader-module       meta-lines       meta->settings       settings->meta)

→ (make-mixin-contract drracket:language:language<%>)

reader-module : module-path?

meta-lines : exact-nonnegative-integer?

meta->settings : (-> string? any/c any/c)

settings->meta : (-> symbol? any/c string?)

This mixin constructs a language level that stores metadata in saved files allowing Drracket to automatically switch back to this language level upon opening them. It overrides get-reader-module, get-metadata, metadata->settings, and get-metadata-lines.

The resulting language level uses the reader from reader-module, and is recognized in files that start with a reader directive for that module path within the first meta-lines lines. Metadata about the language’s settings is marshalled between a string and a usable value (based on a default value) by meta->settings, and between a usable value for a current module (with a symbolic name) by settings->meta.