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# REPL

> Read-Eval-Print Loop (REPL) environment.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

A Read-Eval-Print Loop (REPL) environment is an interactive programming environment which takes individual user inputs (e.g., single expressions), evaluates those inputs, and returns the result. Accordingly, a program written in a REPL environment is executed piecewise and sequentially.

REPL environments find common use in exploratory programming, prototyping, and debugging.

The REPL environment exposed here is available both as a standalone application and as a library which is embeddable in other libraries and applications.

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="usage">

## Usage

```javascript
var REPL = require( '@stdlib/repl' );
```

#### REPL( \[options] )

Returns a `REPL` instance.

```javascript
// Create a new REPL:
var repl = new REPL();

// ...

// Close the REPL:
repl.close();
```

The function accepts the following `options`:

-   **input**: input (readable) stream. Default: [`stdin`][@stdlib/streams/node/stdin].
-   **output**: output (writable) stream. Default: [`stdout`][@stdlib/streams/node/stdout].
-   **sandbox**: boolean indicating whether to run a REPL in a sandboxed context. Default: `false`.
-   **timeout**: number of milliseconds to execute a command before terminating execution. Default: `4294967295`.
-   **isTTY**: boolean indicating whether the input and output streams should be treated like a TTY (terminal) and whether the REPL should use ANSI/VT100 escape codes when writing to the output stream.
-   **inputPrompt**: input prompt. If the input prompt includes the character sequence `%d`, the input prompt includes line numbers. Default: `'In [%d]: '`.
-   **outputPrompt**: output prompt. If the output prompt includes the character sequence `%d`, the output prompt includes line numbers. Default: `'Out[%d]: '`.
-   **welcome**: welcome message.
-   **padding**: number of empty lines between consecutive commands. Default: `1`.
-   **themes**: table containing color themes for syntax highlighting.
-   **load**: file path specifying a JavaScript file to load and evaluate line-by-line (e.g., a previous REPL history file).
-   **save**: file path specifying where to save REPL command history.
-   **log**: file path specifying where to save REPL commands and printed output.
-   **quiet**: boolean indicating whether log information, confirmation messages, and other possible REPL diagnostics should be silenced. Default: `false`.
-   **settings**: object specifying REPL settings.

The function supports specifying the following settings:

-   **autoClosePairs**: boolean indicating whether to automatically insert matching brackets, parentheses, and quotes. Default: `true`.
-   **autoDeletePairs**: boolean indicating whether to automatically delete adjacent matching brackets, parentheses, and quotes. Default: `true`.
-   **autoPage**: boolean indicating whether to automatically page return values having a display size exceeding the visible screen. When streams are TTY, the default is `true`; otherwise, the default is `false`.
-   **bracketedPaste**: boolean indicating whether to enable bracketed-paste mode. When streams are TTY, the default is `true`; otherwise, the default is `false`.
-   **autoDisableBracketedPasteOnExit**: boolean indicating whether to automatically disable bracketed-paste upon exiting the REPL. When streams are TTY and bracketed paste is enabled, the default is `true`; otherwise, the default is `false`.
-   **completionPreviews**: boolean indicating whether to display completion previews for auto-completion. When streams are TTY, the default is `true`; otherwise, the default is `false`.
-   **syntaxHighlighting**: boolean indicating whether to enable syntax highlighting of entered input expressions. When streams are TTY, the default is `true`; otherwise, the default is `false`.
-   **theme**: initial color theme for syntax highlighting. Default: `stdlib-ansi-basic`.

#### REPL.prototype.viewport()

Returns the REPL viewport.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// Query the REPL viewport:
var v = repl.viewport();

// Close the REPL:
repl.close();
```

#### REPL.prototype.createContext()

Returns a REPL context.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Return a new REPL context:
var ctx = repl.createContext();

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.resetContext()

Resets a REPL's execution context.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Reset the REPL context:
repl.resetContext();

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.clearHistory()

Clears a REPL's history.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Clear the REPL history:
repl.clearHistory();

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.clearUserDocs()

Clears user-defined documentation.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Clear user-defined documentation:
repl.clearUserDocs();

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.themes()

Returns a list of all available themes for syntax highlighting.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Fetch all available themes:
var themes = repl.themes();
// returns [...]

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.getTheme( name )

Returns a theme's color palette for syntax highlighting.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Add a user-defined theme:
repl.addTheme( 'myTheme', {
    'keyword': 'red'
});

// Get a theme's color palette:
var theme = repl.getTheme( 'myTheme' );
// returns { 'keyword': 'red' }

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.addTheme( name, theme )

Adds a syntax highlighting theme.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Add a user-defined theme:
repl.addTheme( 'myTheme', {
    'keyword': 'red',
    'variable': 'green'

    // ...
});

// ...

// Close the REPL:
repl.close();
```

The syntax-highlighter supports the following tokens and associated theme fields:

-   **keyword**: keywords (e.g., `var`, `function`, `let`, `const`, `in`, and `class`).
-   **control**: control flow keywords (e.g., `if`, `else`, `try`, `catch`, and `return`).
-   **specialIdentifier**: special identifiers (e.g., `this` and `super`).
-   **string**: string and template literals.
-   **number**: numeric literals.
-   **literal**: reserved literals (e.g., `true`, `false`, `null`, and `undefined`).
-   **regexp**: regular expressions.
-   **command**: built-in REPL commands.
-   **function**: function identifiers.
-   **object**: object identifiers.
-   **variable**: literal identifiers.
-   **name**: variable names.
-   **comment**: line comments.
-   **punctuation**: punctuation symbols (e.g., `;`, `[`, `{`, `,`, and `?`).
-   **operator**: operator symbols (e.g., `+`, `-`, `*`, `=`, `++`, `>=`, and `&&`).

#### REPL.prototype.deleteTheme( name )

Deletes a specified theme from the syntax-highlighter.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Add a user-defined theme:
repl.addTheme( 'myTheme', {
    'keyword': 'red',
    'variable': 'green'

    // ...
});

// Delete the added theme:
repl.deleteTheme( 'myTheme' );

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.renameTheme( oldName, newName )

Renames a specified theme in the syntax-highlighter.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Add a user-defined theme:
repl.addTheme( 'myTheme', {
    'keyword': 'red',
    'variable': 'green'

    // ...
});

// Rename the added theme:
repl.renameTheme( 'myTheme', 'yourTheme' );

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.load( fpath, clbk )

Loads and evaluates a JavaScript file line-by-line.

<!-- run-disable -->

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Load and evaluate a file line-by-line:
repl.load( './path/to/file.js', done );

function done() {
    // Close the REPL:
    repl.close();
}
```

#### REPL.prototype.reset()

Resets a REPL.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Reset the REPL:
repl.reset();

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.clear()

Clears the entire REPL screen and scrollback history.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Clear the REPL:
repl.clear();

// ...

// Close the REPL:
repl.close();
```

This method is **only** applicable for TTY REPLs. In non-TTY REPLs, this method is a non-operation.

#### REPL.prototype.clearLine()

Clears the current line.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Clear the current line:
repl.clearLine();

// ...

// Close the REPL:
repl.close();
```

This method is **only** applicable for TTY REPLs. In non-TTY REPLs, this method is a non-operation.

#### REPL.prototype.clearCommand()

Clears the current REPL command buffer (i.e., clear any command which has been buffered but not yet executed).

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Clear the command buffer:
repl.clearCommand();

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.settings( \[name\[, value]] )

Returns REPL settings.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Retrieve REPL settings:
var o = repl.settings();

// ...

// Close the REPL:
repl.close();
```

To retrieve the current value for a specific setting, provide a `name` argument.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Retrieve current setting value:
var v = repl.settings( 'autoClosePairs' );

// ...

// Close the REPL:
repl.close();
```

To update a specific setting, provide a `value` argument.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Update setting value:
repl.settings( 'autoClosePairs', false );

// ...

// Close the REPL:
repl.close();
```

#### REPL.prototype.close()

Closes a REPL.

```javascript
var debug = require( '@stdlib/streams/node/debug-sink' );

// Create a new REPL:
var repl = new REPL({
    'output': debug()
});

// ...

// Close the REPL:
repl.close();
```

* * *

### Commands

REPL instances support the following commands...

#### addTheme( name, theme )

Adds a syntax highlighting color theme.

```text
// Add color theme:
In [1]: addTheme( 'myTheme', { 'keyword': 'red' } )

// Check updated list of themes:
In [2]: themes()
Out[2]: [ 'stdlib-ansi-basic', 'myTheme' ]
```

#### alias2pkg( arg )

Returns the package name associated with a provided alias or class instance.

```text
In [1]: var v = alias2pkg( 'base.sin' )
Out[1]: '@stdlib/math/base/special/sin'
```

**Note**: only direct instances of documented built-in constructors are supported.

#### alias2related( arg )

Returns aliases related to a specified alias or class instance.

```text
In [1]: var v = alias2related( 'base.sin' )
Out[1]: [...]
```

**Note**: only direct instances of documented built-in constructors are supported.

#### ans

Result of the last successfully executed command.

```text
In [1]: identity( 3.14 )
Out[1]: 3.14

In [2]: ans
Out[2]: 3.14
```

#### assignfrom( workspace, variable )

Reads a value from a specified `workspace`.

```text
In [1]: workspace( 'foobar' );

In [2]: var x = 3.14;

In [3]: workspace( 'barfoo' );

In [4]: var y = assignfrom( 'foobar', 'x' )
Out[4]: 3.14
```

#### assignin( workspace, variable, value )

Assigns a `value` to a `variable` in a specified `workspace`.

```text
In [1]: assignin( 'base', 'x', 3.14 );

In [2]: x
Out[2]: 3.14
```

#### citation()

Prints how to cite stdlib in publications.

```text
In [1]: citation()
```

#### clear()

Clears the entire REPL screen and scrollback history.

```text
In [1]: clear()
```

**Note**: this function is only applicable for TTY REPLs. In non-TTY REPLs, this function is a non-operation.

#### clearHistory()

Clears the REPL history.

```text
In [1]: clearHistory()
```

#### clearUserDocs( \[options] )

Deletes user-defined documentation.

```text
In [1]: clearUserDocs()
```

The function supports the following `options`:

-   **include**: inclusion filter. May be either an array-like `object` or a regular expression.

-   **exclude**: exclusion filter. May be either an array-like `object` or a regular expression.

-   **filter**: filter type. This option is only applicable for array-like `object` filters. Must be one of the following values:

    -   `'alias'`: filter based on documentation alias. If a filter matches a documentation alias, the user-defined documentation is removed.
    -   `'value'`: filter based on object reference. If a filter matches an associated object reference, the user-defined documentation is removed.
    -   `'*'`: filter based on both documentation alias and object reference. If a filter matches either a documentation alias or an associated object reference, the user-defined documentation is removed.

    Default: `'*'`.

```text
In [1]: clearUserDocs( { 'include': /^foo/ } )
```

#### clearvars( \[options] )

Deletes user-defined variables in the current workspace.

```text
In [1]: clearvars()
```

The function supports the following `options`:

-   **include**: variable name inclusion filter. May be either an array-like `object` or a regular expression.
-   **exclude**: variable name exclusion filter. May be either an array-like `object` or a regular expression.

```text
In [1]: clearvars( { 'include': /^foo/ } )
```

#### clearWorkspace( \[name, ]\[options] )

Deletes user-defined variables in a specified workspace.

```text
In [1]: clearWorkspace()
```

By default, the function clears user-defined variables in the current workspace. To clear user-defined variables in a different workspace, provide a workspace `name`.

```text
// Create a new workspace:
In [1]: workspace( 'foobar' );

In [2]: var x = 3.14;

// Switch to another workspace:
In [3]: workspace( 'barfoo' );

In [4]: typeof x
Out[4]: 'undefined'

// List the variables in the previous workspace:
In [5]: varsWorkspace( 'foobar' )
Out[5]: [ 'x' ]

// Delete the variables in the previous workspace:
In [6]: clearWorkspace( 'foobar' );

In [7]: varsWorkspace( 'foobar' )
Out[7]: []

// Navigate to the previous workspace:
In [8]: workspace( 'foobar' );

// Confirm that the variables were deleted:
In [9]: x
Error: x is not defined
```

The function supports the following `options`:

-   **include**: variable name inclusion filter. May be either an array-like `object` or a regular expression.
-   **exclude**: variable name exclusion filter. May be either an array-like `object` or a regular expression.

```text
In [1]: clearWorkspace( 'foobar', { 'include': /^x/ } );
```

#### contributors()

Prints a list of stdlib contributors.

```text
In [1]: contributors()
```

#### copyright()

Prints copyright information.

```text
In [1]: copyright()
```

#### credits()

Prints credits.

```text
In [1]: credits()
```

#### currentWorkspace

Returns the name of the current workspace.

```text
In [1]: currentWorkspace
Out[1]: 'base'
```

#### deleteTheme( name )

Deletes a syntax highlighting color theme.

```text
// Add a color theme:
In [1]: addTheme( 'myTheme', { 'keyword': 'red' } )

// Check list of themes:
In [2]: themes()
Out[2]: [ 'stdlib-ansi-basic', 'myTheme' ]

// Delete the added theme:
In [3]: deleteTheme( 'myTheme' )

// Check updated list of themes:
In [4]: themes()
Out[4]: [ 'stdlib-ansi-basic' ]
```

#### deeprerequire( id )

Re-imports a module, JSON, or local file and all of its associated module dependencies.

```text
In [1]: var foo = require( './foo.js' );

// Modify `./foo.js` and/or its module dependencies...

// Re-import the module:
In [2]: foo = deeprerequire( './foo.js' );
```

Modules can be imported from `node_modules`. Local modules and JSON files can be imported using a relative path (e.g., `'./foo.js'`, `'./../bar.json'`, etc) that will be resolved against the current working directory.

#### deleteWorkspace( \[name] )

Deletes a workspace.

```text
In [1]: workspace( 'foobar' );

In [2]: var x = 3.14;

In [3]: workspace( 'barfoo' );

In [4]: workspaces()
Out[4]: [ 'base', 'foobar', 'barfoo' ]

In [5]: deleteWorkspace( 'foobar' );

In [6]: workspaces()
Out[6]: [ 'base', 'barfoo' ]
```

If not provided an argument, the REPL deletes the current workspace and switches to the `'base'` workspace.

```text
In [1]: workspace( 'foobar' );

In [2]: currentWorkspace
Out[2]: 'foobar'

In [3]: deleteWorkspace();

In [4]: workspaces()
Out[4]: [ 'base' ]

In [5]: currentWorkspace
Out[5]: 'base'
```

**Note**: the `'base'` workspace **cannot** be deleted.

#### donate()

Prints donation information.

```text
In [1]: donate()
```

#### evalin( workspace, expression )

Evaluates an `expression` in a specified `workspace`.

```text
// Create a workspace:
In [1]: workspace( 'foobar' );

// Create and switch to another workspace:
In [2]: workspace( 'barfoo' );

// Attempt to evaluate an expression in the first workspace:
In [3]: evalin( 'foobar', 'var x = 3.14;' );

// Check that nothing has changed in the current workspace:
In [4]: x
Error: x is not defined

// Switch to the first workspace:
In [5]: workspace( 'foobar' );

// Check that the expression was successfully evaluated:
In [6]: x
Out[6]: 3.14
```

#### example( arg )

Runs examples for a specified alias, property, or class instance.

```text
In [1]: example( base.sin )
```

**Note**: only direct instances of documented built-in constructors are supported.

#### getTheme( \[name] )

Returns a syntax highlighting color theme.

```text
// Add a color theme:
In [1]: addTheme( 'myTheme', { 'keyword': 'red' } )

// Get the color theme:
In [2]: getTheme( 'myTheme' )
Out[2]: { 'keyword': 'red' }
```

**Note**: if no theme name is provided, the current theme is returned.

#### help( \[arg] )

Prints help text.

```text
In [1]: help()
```

To print help text for an alias,

```text
In [1]: help( 'base.sin' )

In [2]: help( base.sin )
```

To print help text for a property,

```text
In [1]: help( random.streams.randu.factory )
```

To print help text for a class instance,

```text
In [1]: var x = new Float64Array( 10 );

In [2]: help( x )
```

**Note**: only direct instances of documented built-in constructors are supported.

#### info( arg )

Prints abbreviated help text for a provided alias, property, or class instance.

```text
In [1]: info( base.sin )

In [2]: info( 'base.sin' )
```

**Note**: only direct instances of documented built-in constructors are supported.

#### isKeyword( keyword )

Returns a `boolean` indicating whether a string is a reserved keyword in the REPL environment.

```text
In [1]: isKeyword( 'base.sin' )
Out[1]: true
```

#### license()

Prints license information.

```text
In [1]: license()
```

#### load( fpath )

Loads and evaluates a JavaScript file, such as a REPL history file, line-by-line.

```text
In [1]: load( './path/to/file.js' )
```

#### loadWorkspace( name\[, options] )

Loads variables from a specified workspace into the current workspace.

```text
In [1]: workspace( 'foobar' );

In [2]: var x = 3.14;

In [3]: workspace( 'barfoo' );

In [4]: typeof x
Out[4]: 'undefined'

In [5]: loadWorkspace( 'foobar' );

In [6]: x
Out[6]: 3.14
```

The function supports the following `options`:

-   **include**: variable name inclusion filter. May be either an array-like `object` or a regular expression.
-   **exclude**: variable name exclusion filter. May be either an array-like `object` or a regular expression.
-   **override**: `boolean` indicating whether to override existing workspace variables. Default: `true`.

```text
In [1]: workspace( 'foobar' );

In [2]: var x = 3.14, y = 6.28;

In [3]: workspace( 'barfoo' );

In [4]: typeof x
Out[4]: 'undefined'

In [5]: loadWorkspace( 'foobar', { 'include': /^x/ } );

In [6]: x
Out[6]: 3.14

In [7]: typeof y
Out[7]: 'undefined'
```

#### logStart( fpath )

Starts logging commands and printed output to a specified file path.

```text
// TODO
```

#### logStop( id )

Stops logging commands and printed output to a file path associated with a specified record identifier.

```text
// TODO
```

#### presentationStart( \[text, ]\[options] )

Starts a REPL [presentation][@stdlib/repl/presentation].

```text
In [1]: var id = presentationStart( 'beep\n---\nboop\n' );
```

The function accepts the following `options`:

-   **borderTop**: top border character sequence. Default: `'*'`.
-   **borderBottom**: bottom border character sequence. Default: `'*'`.
-   **borderLeft**: left border character sequence. Default: `'* '`.
-   **borderRight**: right border character sequence. Default: `' *'`.
-   **counter**: slide counter. Can either be `true`, `false`, or `'progress'`. Default: `false`.
-   **width**: [presentation][@stdlib/repl/presentation] width. If `null`, the [presentation][@stdlib/repl/presentation] width is either computed based on the screen size (if a REPL output stream is TTY) or set to `80` characters. Default: `null`.
-   **height**: [presentation][@stdlib/repl/presentation] height. If `null`, the [presentation][@stdlib/repl/presentation] height is either computed based on the screen size (if a REPL output stream is TTY) or set to `25` rows. Default: `null`.
-   **workspace**: REPL workspace name. A [presentation][@stdlib/repl/presentation] adds commands to the specified workspace, thus allowing [presentation][@stdlib/repl/presentation] navigation and interaction. Default: `'presentation-<n>'`, where `n` is an assigned [presentation][@stdlib/repl/presentation] identifier.
-   **load**: file path specifying a [presentation][@stdlib/repl/presentation] file to load. If presentation `text` is provided, this option is **ignored**. Otherwise, this option is **required**.
-   **watch**: `boolean` indicating whether to watch a [presentation][@stdlib/repl/presentation] source file for changes. This option is only applicable if not provided presentation `text` and the `options` object specifies a presentation file to load. Default: `false`.
-   **autoClear**: `boolean` indicating whether to automatically clear the screen before writing a rendered slide to the REPL. Default: `true`.
-   **loop**: `boolean` indicating whether to "loop" a presentation. Default: `false`.

A few notes:

-   When not provided presentation `text`, an options argument **must** specify a presentation file to load.
-   If a specified workspace already exists, the workspace is silently cleared and a new [presentation][@stdlib/repl/presentation] bound. In order to preserve an existing workspace, specify an alternative presentation workspace name.

#### presentationStop( \[id] )

Stops a REPL [presentation][@stdlib/repl/presentation].

```text
In [1]: var id = presentationStart( 'beep\n---\nboop\n' );

In [2]: presentationStop();
```

A few notes:

-   If provided a presentation identifier, the corresponding [presentation][@stdlib/repl/presentation] is stopped. Otherwise, assuming the function is invoked in a presentation workspace, the current [presentation][@stdlib/repl/presentation] is stopped.
-   When stopping a REPL [presentation][@stdlib/repl/presentation], the presentation's REPL workspace is both **cleared** and **deleted**.

#### quit()

Exits the REPL.

```text
In [1]: quit()
```

#### renameTheme( oldName, newName )

Renames a syntax highlighting color theme.

```text
// Add a color theme:
In [1]: addTheme( 'myTheme', { 'keyword': 'red' } )

// Check list of themes:
In [2]: themes()
Out[2]: [ 'stdlib-ansi-basic', 'myTheme' ]

// Rename the added theme:
In [3]: getTheme( 'myTheme', 'yourTheme' )

// Check updated list of themes:
In [4]: themes()
Out[4]: [ 'stdlib-ansi-basic', 'yourTheme' ]
```

#### renameWorkspace( oldName, newName )

Renames a workspace.

```text
// Create a new workspace:
In [1]: workspace( 'foobar' );

In [2]: var x = 3.14;

// List current workspaces:
In [3]: workspaces()
Out[3]: [ 'base', 'foobar' ]

// Switch to another workspace:
In [4]: workspace( 'barfoo' );

// List current workspaces:
In [5]: workspaces()
Out[5]: [ 'base', 'foobar', 'barfoo' ]

// Rename the first workspace:
In [6]: renameWorkspace( 'foobar', 'beepboop' );

// Check the updated list of workspaces:
In [7]: workspaces()
Out[7]: [ 'base', 'barfoo', 'beepboop' ]

// Switch to the renamed workspace:
In [8]: workspace( 'beepboop' );

// Confirm that workspace contains previously defined variables:
In [9]: x
Out[9]: 3.14
```

**Note**: the new workspace name must **not** already exist. The only exception is when the old name and the new name are the same; in which case, invoking this command is a non-operation.

**Note**: as a `'base'` workspace must **always** exist, when renaming the `'base'` workspace, variables from the `'base'` workspace are simply copied to a new workspace and the `'base'` workspace cleared of user-defined variables.

#### require( id )

Imports a module, JSON, or local file.

```text
In [1]: var crypto = require( 'crypto' );
```

Modules can be imported from `node_modules`. Local modules and JSON files can be imported using a relative path (e.g., `'./foo.js'`, `'./../bar.json'`, etc) that will be resolved against the current working directory.

#### rerequire( id )

Re-imports a module, JSON, or local file.

```text
In [1]: var foo = require( './foo.js' );

// Modify `./foo.js`...

// Re-import the module:
In [2]: foo = rerequire( './foo.js' );
```

Modules can be imported from `node_modules`. Local modules and JSON files can be imported using a relative path (e.g., `'./foo.js'`, `'./../bar.json'`, etc) that will be resolved against the current working directory.

#### rerun( \[arg] )

Reruns previous commands.

```text
In [1]: 1+1
Out[1]: 2

In [2]: rerun()
```

By default, the command re-executes the previous command. If provided an `integer`, the previous `n` commands are re-executed.

```text
In [1]: 1+1
Out[1]: 2

In [2]: 2+2
Out[2]: 4

In [3]: rerun( 2 )
```

If provided a regular expression, the most recent command matching the regular expression is rerun.

```text
In [1]: var x = base.sin( 3.14 );

In [2]: 1+1
Out[2]: 2

In [3]: rerun( /base\.sin/ )
```

If provided an `array` of command identifiers, the command corresponding to each identifier is rerun.

```text
In [1]: 1+1
Out[1]: 2

In [2]: 2+2
Out[2]: 4

In [3]: 3+3
Out[3]: 6

In [4]: rerun( [ 1, 3 ] )
```

If provided a subsequence `string`, the command corresponding to each resolved command identifier is rerun.

```text
In [1]: 1+1
Out[1]: 2

In [2]: 2+2
Out[2]: 4

In [3]: 3+3
Out[3]: 6

In [4]: rerun( '1:3:2' )
```

**WARNING**: be careful when re-evaluating previously executed `rerun` commands, as this can lead to infinite execution loops.

#### reset()

Resets the REPL.

```text
In [1]: reset()
```

#### save( fpath )

Saves previous commands to a specified file path.

```text
// TODO
```

#### saveStart( fpath )

Starts saving commands to a specified file path.

```text
// TODO
```

#### saveStop( id )

Stops saving commands to a file path associated with a specified record identifier.

```text
// TODO
```

#### settings( \[name\[, value]] )

Displays REPL settings.

```text
In [1]: settings()
```

To retrieve the current value for a specific setting, provide a `name` argument.

```text
In [1]: settings( 'autoClosePairs' )
```

To update a specific setting, provide a `value` argument.

```text
In [1]: settings( 'autoClosePairs', false )
```

#### themes()

Returns a list of all available syntax highlighting color themes.

```text
// Add a color theme:
In [1]: addTheme( 'myTheme', { 'keyword': 'red' } )

// Check list of themes:
In [2]: themes()
Out[2]: [ 'stdlib-ansi-basic', 'myTheme' ]
```

#### tutorial( \[name, \[options]] )

Starts a tutorial.

```text
In [1]: var id = tutorial( 'repl' );
```

The function accepts the following `options`:

-   **borderTop**: top border character sequence. Default: `'*'`.
-   **borderBottom**: bottom border character sequence. Default: `'*'`.
-   **borderLeft**: left border character sequence. Default: `'* '`.
-   **borderRight**: right border character sequence. Default: `' *'`.
-   **counter**: slide counter. Can either be `true`, `false`, or `'progress'`. Default: `progress`.
-   **workspace**: REPL workspace name. A tutorial [presentation][@stdlib/repl/presentation] adds commands to the specified workspace, thus allowing tutorial navigation and interaction. Default: `'tutorial-<name>-<n>'`, where `name` is the tutorial `name` and `n` is an assigned tutorial [presentation][@stdlib/repl/presentation] identifier.
-   **autoClear**: `boolean` indicating whether to automatically clear the screen before writing a rendered tutorial slide to the REPL. Default: `true`.

A few notes:

-   When not provided a tutorial `name`, the function prints a list of available tutorials.
-   If a specified workspace already exists, the workspace is silently cleared and a new tutorial [presentation][@stdlib/repl/presentation] bound. In order to preserve an existing workspace, specify an alternative tutorial workspace name.

#### userDoc( alias, \[ref,] doc )

Adds user-defined documentation.

```text
In [1]: function foo() {};

In [2]: userDoc( 'foo', foo, '\nfoo()\n    Foo bar.\n' );

In [3]: help( foo )
```

If user-defined documentation already exists for the provided alias, the current documentation is overwritten.

```text
In [1]: function foo() {};

In [2]: userDoc( 'foo', foo, '\nfoo()\n    Foo bar.\n' );

In [3]: help( foo )

foo()
    Foo bar.


In [4]: userDoc( 'foo', foo, '\nfoo()\n    Beep boop.\n' );

In [5]: help( foo )

foo()
    Beep boop.


```

#### vars( \[options] )

Returns a list of variable names in the current workspace.

```text
In [1]: var x = 3.14;

In [2]: vars()
Out[2]: [ 'x' ]
```

The function supports the following `options`:

-   **include**: regular expression variable name inclusion filter.
-   **exclude**: regular expression variable name exclusion filter.
-   **types**: array-like `object` containing variable type inclusion filter(s).
-   **details**: `boolean` indicating whether to include additional variable details, such as variable type, contents, etc. Default: `false`.

```text
In [1]: var x = 3.14;

In [2]: vars( { 'details': true } )
```

#### varsWorkspace( \[name, ]\[options] )

Returns a list of variable names in a specified workspace.

```text
In [1]: var x = 3.14;

// List variable names in the current workspace:
In [2]: varsWorkspace()
Out[2]: [ 'x' ]

In [3]: workspace( 'foo' );

In [4]: varsWorkspace( 'base' )
Out[4]: [ 'x' ]
```

The function supports the following `options`:

-   **include**: regular expression variable name inclusion filter.
-   **exclude**: regular expression variable name exclusion filter.
-   **types**: array-like `object` containing variable type inclusion filter(s).
-   **details**: `boolean` indicating whether to include additional variable details, such as variable type, contents, etc. Default: `false`.

```text
In [1]: var x = 3.14;

In [2]: workspace( 'foo' );

In [3]: varsWorkspace( 'base', { 'details': true } )
```

#### workspace( name )

Switches to a specified workspace.

```text
In [1]: workspace( 'foobar' );

In [2]: var x = 3.14;

In [3]: workspace( 'beepboop' );

In [4]: x
Error: x is not defined

In [5]: workspace( 'foobar' );

In [6]: x
Out[6]: 3.14
```

If a workspace with the specified `name` does not exist, the workspace is created.

#### workspaces( \[options] )

Returns a list of workspace names.

```text
In [1]: workspaces()
Out[1]: [ 'base' ]
```

The function supports the following `options`:

-   **include**: regular expression workspace name inclusion filter.
-   **exclude**: regular expression workspace name exclusion filter.
-   **details**: `boolean` indicating whether to include additional workspace details, such as variable names, types, contents, etc. Default: `false`.

```text
In [1]: workspaces( { 'details': true  } )
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

* * *

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var join = require( 'path' ).join;
var REPL = require( '@stdlib/repl' );

function onExit() {
    console.log( '' );
    console.log( 'REPL closed.' );
}

// Create a new REPL:
var repl = new REPL();
repl.on( 'exit', onExit );

// Load a history file:
repl.load( join( __dirname, 'examples', 'history.txt' ), done );

function done() {
    // Close the REPL:
    repl.close();
}
```

</section>

<!-- /.examples -->

<!-- Section for describing a command-line interface. -->

* * *

<section class="cli">

## CLI

<!-- CLI usage documentation. -->

<section class="usage">

### Usage

```text
Usage: stdlib-repl [options]

Options:

  -h, --help                    Print this message.
  -V, --version                 Print the package version.
      --welcome <message>       Welcome message.
      --input-prompt <prompt>   Input prompt. Default: 'In [%d]: '.
      --output-prompt <prompt>  Output prompt. Default: 'Out[%d]: '.
      --padding <padding>       Empty lines between commands. Default: 1.
      --load <filepath>         JavaScript file to evaluate line-by-line.
      --save <filepath>         File to save REPL command history.
      --logfile <filepath>      File to log REPL commands and printed output.
      --timeout <timeout>       Milliseconds before terminating a command.
      --quiet                   Disable printing of REPL logs and diagnostics.
```

</section>

<!-- /.usage -->

<!-- CLI usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- CLI usage examples. -->

<section class="examples">

### Examples

```bash
$ stdlib-repl
```

</section>

<!-- /.examples -->

</section>

<!-- /.cli -->

<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="references">

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[@stdlib/streams/node/stdin]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/streams/node/stdin

[@stdlib/streams/node/stdout]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/streams/node/stdout

[@stdlib/repl/presentation]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/repl/presentation

</section>

<!-- /.links -->