► |  | Reference: PLT Scheme

1 | Language Model
2 | Syntactic Forms
3 | Datatypes
4 | Structures
5 | Classes and Objects
6 | Units
7 | Contracts
8 | Pattern Matching
9 | Control Flow
10 | Concurrency
11 | Macros
12 | Input and Output
13 | Reflection and Security
14 | Operating System
15 | Memory Management
16 | Unsafe Operations
17 | Running PLT Scheme
| Bibliography
| Index

▼ | 17 | Running PLT Scheme

17.1 | Running Mz Scheme or Mr Ed
17.2 | Libraries and Collections
17.3 | Interactive Help
17.4 | Interactive Module Loading

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help

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#### 17.3`` Interactive Help

(require scheme/help)

The bindings documented in this section are provided by the scheme/help and scheme/init libraries, which means that they are available when mzscheme is started with no command-line arguments. They are not provided by scheme/base or scheme.

help

(help string ...)

(help id)

(help id #:from module-path)

(help #:search datum ...)

For general help, see the main documentation page.

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 scheme/gui) ; does not work in mzscheme
(require (for-label scheme/gui)) ; ok in mzscheme
(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 #:from module-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% #:from scheme/gui) ; equivalent to the above

The (help #:search datum ...) 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.”

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