Translate text

Put each language's text in a table, a .zon file in your project's resources. Each field names a key, and its value is the text to show for that key:

// resources/locales/fr.zon
.{
    .@"menu.play" = "Jouer",
    .@"menu.quit" = "Quitter",
}

Quote a key with .@"..." when it has dots or spaces in it. Every value must be a string.

Add the tables and choose a locale

Tell app.localization which file holds each locale, then choose one, usually in init:

try app.localization.addTable("en", .init("resources/locales/en.zon"));
try app.localization.addTable("fr", .init("resources/locales/fr.zon"));
try app.localization.setLocale(app.resources(), "fr");

setLocale reads only the chosen locale's table. If there is no table for a regional locale such as fr-CA, it uses the language's table (fr). It fails with UnknownLocale when neither was added, and with InvalidLocaleTable when the file isn't keys and strings. If it fails, the locale already in use stays. Call it again whenever the player picks another language.

Look up text

// Borrowed until the locale changes; fall back to your own text if the key is missing.
const play = app.localization.lookup("menu.play") orelse "Play";

// Or a copy you own, with an error for a missing key.
const quit = try app.localization.text(gpa, "menu.quit");
defer gpa.free(quit);

lookup returns null for a key the table doesn't have. text returns MissingTranslation in that case, and NoLocale before any locale has been chosen. Neither one returns the key itself as the text, so you can tell when a translation is missing. app.localization.currentLocale() gives the locale in use, as its table was added.