Release Localize version 0.50.0 · elixir-localize/localize

[0.50.0] — July 15th, 2026

Localize.LanguageTag.remove_likely_subtags/2 and !/2 accept favor: :script | :region to select the TR35 removal variant (zh-Hant-TW minimizes to "zh-Hant" or "zh-TW"), verified against the full CLDR likely-subtags test data.
The MessageFormat working group's :test:function, :test:format and :test:select registry functions are implemented, so the WG conformance suite's selection-mechanics and fallback cases now run.
The MF2 numeric functions accept the signDisplay option (auto, always, exceptZero, negative, never), with the plus sign taken from the locale's number symbols.
An MF2 pattern expression that re-annotates a declared variable operates on the declaration's original value, and numeric functions inherit unset options from a numeric declaration — .local $x = {41 :integer signDisplay=always} rendered with {$x :offset add=1} produces "+42".
The locale download base URL can be overridden with config :localize, locale_base_url: "..." for deployments mirroring the locale files; downloads are verified against the bundled hash manifest regardless of source.

An unannotated MF2 placeholder with a numeric operand formats with the locale-aware :number default ({$pi} renders "3.142" in en and "3,142" in fr), matching the MF2 implicit formatting rules; previously the value was stringified verbatim.
MessageFormat 2 follows the specification's error semantics: unknown functions are an error (Localize.FormatError reason :unknown_function) instead of formatting the operand, and data-model validation rejects duplicate declarations, duplicate option names, and duplicate variants (NFC-normalized keys) with dedicated error reasons.
MessageFormat 2 function validation is strict per TR35: the select option must be a literal set directly on the selector expression, digit-size options must be non-negative integers, string operands of numeric functions must match the number-literal production, and :currency, :unit, :date, :time and :datetime are rejected as selectors.
Localize.Number.Format.Options is documented again: validate_options/2 is the supported way to pre-resolve formatting options for hot loops (as the Performance guide describes), so the module is part of the public API.
The TR35 conformance guide documents the MessageFormat 2 working-group suite exclusions precisely: unknown-function fallback, duplicate declaration/option validation, select and digit-size option validation, u:dir/u:id expression options, and the :isolate bidi strategy deviation.

Localize.Currency.currencies_for_locale/2,3, currencies_for_locale!/2,3, currency_strings/2,3 and currency_strings!/2,3 take the include/exclude filters as :only and :except options instead of positional arguments. The positional forms still work but are deprecated and will be removed by Localize 1.0 and no later than December 2026.

Calendar- and provider-module probes in date/datetime formatting (era year, day of era, ISO week and day of year, day of week, CLDR calendar type) and Localize.Locale.Provider.allow_download?/1 ensure the module is loaded before function_exported?/3, so a cold module no longer silently takes the gregorian or default fallback branch.

Localize.Locale.Provider.locale_file_name/1 rejects locale identifiers that do not have the shape of a CLDR locale id, as defense in depth for the cache-path and download-URL interpolations.