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4.5.1 Source Annotations for Documentation
provide/ doc
require/ doc
proc-doc/ names
4.5.2 Extracting Documentation from Source

4.5 In-Source Documentation

The scribble/srcdoc and scribble/extract libraries support writing documentation withing the documentation code along with an export contract, similar to using JavaDoc. With this approach, a single contract specification is used both for the run-time contract and the documentation of an exported binding.

The scribble/srcdoc library provides forms for exporting a binding with associated documentation. The scribble/extract library is used to pull scribble/srcdoc-based documentation into a Scribble document (perhaps for multiple libraries).

Although documentation is written with a library’s implementation when using scribble/srcdoc, the documentation creates no run-time overhead for the library. Similarly, typesetting the documentation does not require running the library. The two phases (run time versus documentation time) are kept separate in much the same way that the module system keeps expansion-time code separate from run-time code.

For an example use, see the "file" collection’s "gif.rkt" source file and the corresponding extraction in "scribblings/gif.scrbl". As that example illustrates, prefixing the module declaration with

  #reader scribble/reader

enables the @-reader, which is handy for writing documentation expressions.

4.5.1 Source Annotations for Documentation

 (require scribble/srcdoc)

(provide/doc spec ...)
Like provide or provide/contract, but each spec uses a documentation transformer to describe the exported identifier and its contract.

The currently supported documentation transformers are proc-doc, proc-doc/names, parameter-doc, and thing-doc.

(require/doc require-spec ...)
Like require, but for bindings that are needed at documentation time (and documentation-expansion time, etc.) instead of run time (and expansion time, etc.). A require-doc form has no effect on a normal use of the library; it affects only documentation extraction.

Typically, a library that uses scribble/srcdoc includes at least (require/doc scribble/base scribble/manual) to get core Racket forms and basic Scribble functions to use in documentation expressions.

(proc-doc/names id contract ((arg-id ...) ((arg-id default-expr) ...)) desc-expr)
(proc-doc/names id case-contract ((arg-id ...) ((arg-id default-expr) ...)) desc-expr)
contract = (-> arg ... result)
  | (->* (mandatory ...) (optional ...) result)
mandatory = contract-expr
  | keyword contract-expr
optional = contract-expr
  | keyword contract-expr
case-contract = (case-> (-> arg ... result) ...)
When used in provide/doc, exports id with the contract described by contract or case-contract, just like using provide/contract.

The arg-ids specify the names of arguments, which are not normally written as part of a contract. They are combined with the contract expression to generate the description of the binding in the documentation via defproc. The (arg-id default-expr) pairs specify the names and default values of the optional arguments.

The desc-expr is a documentation-time expression that produces prose to describe the exported binding – that is, the last part of the generated defproc, so the description can refer to the arg-ids using racket.

The normal requires of the enclosing library are effectively converted into for-label requires when generating documentation, so that identifiers in the contracts are linked to their corresponding documentation. Similarly, any binding that is available in the run-time phase of of the enclosing library can be referenced in documentation prose using the racket form.

(proc-doc id contract desc-expr)
contract = (-> result)
  | (->d (arg ...) () (values [id result] ...))
  | (->d (arg ...) () #:pre-cond expression (values [id result] ...))
  | (->d (arg ...) () [id result])
  | (->d (arg ...) () #:pre-cond expression [id result])
  | (->d (arg ...) () #:rest id rest [id result])
Like proc-doc, but supporting contract forms that embed argument names. Only a subset of ->d forms are currently supported.

(thing-doc id contract-expr dec-expr)
Like proc-doc, but for an export of an arbitrary value.

(parameter-doc id (parameter/c contract-expr) arg-id desc-expr)
Like proc-doc, but for exporting a parameter.

4.5.2 Extracting Documentation from Source

 (require scribble/extract)

(include-extracted module-path)
Expands to a sequence of documentation forms extracted from module-path, which is expected to be a module that uses scribble/srcdoc.

(provide-extracted module-path)
Similar to include-extracted, but the documentation is packaged and exported as exported, instead of left inline.

Use this form in combination with include-previously-extracted when documentation from a single source is to be split and typeset among multiple documentation locations. The provide-extracted form extracts the documentation once, and then include-previously-extracted form extracts documentation for specific bindings as needed.

(include-previously-extracted module-path regexp)
Similar to include-extracted, but instead of referring to the source that contains its own documentation, module-path refers to a module that uses provide-extracted. The include-previously-extracted form expands to documentation forms for all identifiers whose string forms match regexp.