menu🔗ℹ

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.

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.

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?.

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 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.

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.

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.

8 Accessors🔗ℹ