5.1 Overview🔗ℹ

A menu is represented as a tree. A menu consists of menu items, and a menu item may optionally contain a submenu.

Menu identifiers are symbols. Menu item titles are strings. Icons are stored as strings and may be supplied either as #f, strings, or URL values.

The module does not display menus itself. It provides the menu data structure used by higher layers.

5.2 Internal Representation🔗ℹ

Internally, menus are represented by transparent structure values. These structure constructors and predicates are not exported directly. The public API uses constructor procedures and helper functions operating on those internal values.

5.3 Predicates🔗ℹ

A value is recognized as a menu if it is an internal menu structure whose item list is a list of internal menu items, and every submenu recursively also satisfies is-wv-menu?.

5.4 Constructors🔗ℹ

If the first argument is a symbol, it is used as the menu identifier and removed from the remaining arguments. Otherwise the menu identifier is #f.

If the first remaining argument is itself a list, that list is used as the item list. Otherwise all remaining arguments are treated as menu items.

This means the following forms are accepted:

(wv-menu item ...)

(wv-menu 'some-id item ...)

(wv-menu (list item ...))

(wv-menu 'some-id (list item ...))

The result is a value satisfying is-wv-menu?.

id must be a symbol and title must be a string.

icon-url must be #f, a string, or a URL value. If it is a URL value, it is converted to a string using url->string before being stored.

submenu must be #f or a value satisfying is-wv-menu?.

separator must be a boolean.

If any argument does not satisfy these conditions, an exception is raised.

5.5 Traversal and Lookup🔗ℹ

If a menu item contains a submenu, that submenu is traversed recursively.

The callback is invoked only for menu items that are reached by the traversal. The function returns #t.

If menu does not satisfy is-wv-menu?, an exception is raised. If id is not a symbol, an exception is raised. If no item with the given id can be found, an exception is raised.

After the callback has been applied, the original menu value is returned.

5.6 Mutation🔗ℹ

title must be a string. The function returns the original menu value.

icon-url must be #f, a string, or a URL value. If it is a URL value, it is converted to a string using url->string before being stored.

The function returns the original menu value.

cb must be a procedure. The function returns the original menu value.

5.7 Conversion🔗ℹ

The conversion first builds a hash-based representation of the menu and then writes that representation with write-json.

In the JSON representation:

• the top-level object contains the keys 'menu and 'id

• menu item identifiers are converted to strings

• menu item titles are written under the key 'name

• an icon is written only if it is not #f

• a submenu is written recursively only if it is not #f

• a separator flag is written only if it is not #f

The 'id field of the top-level menu is also converted to a string in the JSON output.

5.8 Accessors🔗ℹ