18.3Interactive Help🔗 i

The help form searches the documentation and opens a web browser (using the user’s selected browser) to display the results.

See net/sendurl for information on how the user’s browser is launched to display help information.

A simple help or (help ) form opens the main documentation page.

The (help string... ) form—using literal strings, as opposed to expressions that produce strings—performs a string-matching search. For example,

(help "web browser""firefox")

searches the documentation index for references that include the phrase “web browser” or “firefox.”

A (help id) form looks for documentation specific to the current binding of id. For example,

(require net/url)

(help url->string )

opens a web browser to show the documentation for url->string from the net/url library.

For the purposes of help , a for-label require introduces a binding without actually executing the net/url library—for cases when you want to check documentation, but cannot or do not want to run the providing module.

(require racket/gui);does not work in racket

(require (for-label racket/gui));ok in racket

(help frame% )

If id has no for-label and normal binding, then help lists all libraries that are known to export a binding for id.

The (help id#:frommodule-path) variant is similar to (help id), but using only the exports of module-path. (The module-path module is required for-label in a temporary namespace.)

(help frame% #:fromracket/gui);equivalent to the above

The (help #:searchdatum... ) form is similar to (help string... ), where any non-string form of datum is converted to a string using display . No datum is evaluated as an expression.

For example,

(help #:search"web browser"firefox)

also searches the documentation index for references that include the phrase “web browser” or “firefox.”