The language CLISP uses to communicate with the user can be one of

This is controlled by the SYMBOL-MACRO CUSTOM:*CURRENT-LANGUAGE*, which can be set at run time as well as using the -L command line option. If you wish to change the locale directory at run time too, you can do that by setting CUSTOM:*CURRENT-LANGUAGE* to a CONS cell, whose CAR is the language (a SYMBOL, one of the above), and whose CDR is the new locale directory.

More languages can be defined through the macro I18N:DEFLANGUAGE: (I18N:DEFLANGUAGE language). For such an additional language to take effect, you must install the corresponding message catalog, or translate the messages yourself, using GNU gettext and Emacs po-mode.

This works only for strings. For arbitrary language-dependent Lisp objects, you define one through the macro I18N:DEFINTERNATIONAL: (I18N:DEFINTERNATIONAL symbol &OPTIONAL (default-language T)) and add language-dependent values through the macro I18N:DEFLOCALIZED: (I18N:DEFLOCALIZED symbol language value-form) (One such form for each language. Languages without an assigned value will be treated like the default-language.) You can then access the localized value by calling I18N:LOCALIZED: (I18N:LOCALIZED symbol &OPTIONAL language)