6.25.1 Internationalization with Guile

In order to make use of the functions described thereafter, the (ice-9 i18n) module must be imported in the usual way:

(use-modules (ice-9 i18n))

The (ice-9 i18n) module provides procedures to manipulate text and other data in a way that conforms to the cultural conventions chosen by the user. Each region of the world or language has its own customs to, for instance, represent real numbers, classify characters, collate text, etc. All these aspects comprise the so-called “cultural conventions” of that region or language.

Computer systems typically refer to a set of cultural conventions as a locale. For each particular aspect that comprise those cultural conventions, a locale category is defined. For instance, the way characters are classified is defined by the LC_CTYPE category, while the language in which program messages are issued to the user is defined by the LC_MESSAGES category (see General Locale Information for details).

The procedures provided by this module allow the development of programs that adapt automatically to any locale setting. As we will see later, many of these procedures can optionally take a locale object argument. This additional argument defines the locale settings that must be followed by the invoked procedure. When it is omitted, then the current locale settings of the process are followed (see setlocale).

The following procedures allow the manipulation of such locale objects.

Scheme Procedure: make-locale category-list locale-name [base-locale]

C Function: scm_make_locale (category_list, locale_name, base_locale)

Return a reference to a data structure representing a set of locale datasets. locale-name should be a string denoting a particular locale (e.g., "aa_DJ") and category-list should be either a list of locale categories or a single category as used with setlocale (see setlocale). Optionally, if base-locale is passed, it should be a locale object denoting settings for categories not listed in category-list.

The following invocation creates a locale object that combines the use of Swedish for messages and character classification with the default settings for the other categories (i.e., the settings of the default C locale which usually represents conventions in use in the USA):

(make-locale (list LC_MESSAGES LC_CTYPE) "sv_SE")

The following example combines the use of Esperanto messages and conventions with monetary conventions from Croatia:

(make-locale LC_MONETARY "hr_HR"
             (make-locale LC_ALL "eo_EO"))

A system-error exception (see Handling Errors) is raised by make-locale when locale-name does not match any of the locales compiled on the system. Note that on non-GNU systems, this error may be raised later, when the locale object is actually used.

Scheme Procedure: locale? obj

C Function: scm_locale_p (obj)

Return true if obj is a locale object.

Scheme Variable: %global-locale

C Variable: scm_global_locale

This variable is bound to a locale object denoting the current process locale as installed using setlocale () (see Locales). It may be used like any other locale object, including as a third argument to make-locale, for instance.