Description
Common Locale Data Repository (CLDR) functions for Elixir to localize and format numbers, dates, lists and units with support for over 500 locales for internationalized (i18n) and localized (L10N) applications.
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README
Getting Started with Cldr
CI Using Github Actions {: .info}
If you are using Github Actions for your CI you may find there is an SSL error when compilation is downloading locales. Community feedback indicates that testing with OTP-25 resolves the issue.
If you use Cldr.Plug.PutLocale
Please note that as of ex_cldr
version 2.29.9, the CLDR-based plugs have been extracted to their own ex_cldr_plugs
library. you will need to add that dependency to your application. For example:
# in mix.exs
def deps do
[
{:ex_cldr, "~> 2.33"},
{:ex_cldr_plugs, "~> 1.2"},
...
]
end
Introduction
ex_cldr
is an Elixir library for the Unicode Consortium's Common Locale Data Repository (CLDR). The intentions of CLDR, and this library, is to simplify the locale specific formatting and parsing of numbers, lists, currencies, calendars, units of measure and dates/times. As of April 6th 2022 and ex_cldr
Version 2.28.0, ex_cldr
is based upon CLDR version 41.0.
The first step is to define a module that will host the desired ex_cldr
configuration and the functions that serve as the public API. This module is referred to in this documentation as a backend
module. For example:
defmodule MyApp.Cldr do
@moduledoc """
Define a backend module that will host our
Cldr configuration and public API.
Most function calls in Cldr will be calls
to functions on this module.
"""
use Cldr,
locales: ["en", "fr", "zh", "th"],
default_locale: "en"
end
This strategy means that different configurations can be defined and it also
means that one Cldr
implementation won't interfer with implementations in other,
potentially dependent, applications.
The functions you are mostly likely to use are:
MyApp.Cldr.default_locale/0
MyApp.Cldr.put_locale/1
MyApp.Cldr.get_locale/0
MyApp.Cldr.known_locale_names/0
MyApp.Cldr.Locale.new/1
MyApp.Cldr.validate_locale/1
Use Case
Use this library if you need to:
Support multiple languages and locales in your application
Support formatting numbers, dates, times, date-times, units and lists in one language or many
Need to access the data maintained in the CLDR repository in a functional manner
Parse an Accept-Language http header or a language tag
It is highly likely that you will also want to install one or more of the dependent packages that provide localization and formatting for a particular data domain. See Additional Cldr Packages below.
Elixir Version Requirements
- ex_cldr requires Elixir 1.11 or later.
Installation
Add ex_cldr
and the JSON library of your choice as a dependencies to your mix
project:
defp deps do
[
{:ex_cldr, "~> 2.33"},
# Poison or any other compatible json library
# that implements `encode!/1` and `decode!/1`
# :jason is recommended
{:jason, "~> 1.0"}
# {:poison, "~> 2.1 or ~> 3.0"}
]
end
then retrieve ex_cldr
and the JSON library from hex:
mix deps.get
mix deps.compile
Additional Cldr Packages
ex_cldr
includes only basic functions to maintain the CLDR data repository in an accessible manner and to manage locale definitions. Additional functionality is available by adding additional packages:
- Plugs for setting the locale from an HTTP request: ex_cldr_plugs
- Number formatting: ex_cldr_numbers
- List formatting: ex_cldr_lists
- Unit formatting: ex_cldr_units
- Date/Time/DateTime formatting: ex_cldr_dates_times
- Route localization for Phoenix: ex_cldr_routes
- Locale name localisation: ex_cldr_locale_display
- HTML select helpers: ex_cldr_html
- Calendars: ex_cldr_calendars
- Calendar formatting: ex_cldr_calendars_format
- Printf-like formatting: ex_cldr_print
- Collation: ex_cldr_collation
- ICU Message formatting: ex_cldr_messages
- Territories localization and information: ex_cldr_territories by @Schultzer
- Languages localization: ex_cldr_languages by @lostkobrakai
Each of these packages includes ex_cldr
as a dependency so configuring any of these additional packages will automatically install ex_cldr
.
Configuration
Cldr
attempts to maximise runtime performance at the expense of additional compile time. Where possible Cldr
will create functions to encapsulate data at compile time. To perform these optimizations for all 541 locales known to Cldr wouldn't be an effective use of your time or your computer's. Therefore Cldr
requires that you configure the locales you want to use.
The preferred way to configure Cldr
is to define the configuration in your backend module. This removes any dependency on your mix.exs
and therefore simplifies deployment as a release.
Backend Module Configuration
The preferred configuration method is to define the configuration in the backend module. Using the backend configuration in config.exs
is discouraged and will result in a warning at compile time. The configuration keys are the same so the preferred way to achieve the same configuration as defined in the global example is:
defmodule MyApp.Cldr do
use Cldr,
default_locale: "en",
locales: ["fr", "en", "bs", "si", "ak", "th"],
add_fallback_locales: false,
gettext: MyApp.Gettext,
data_dir: "./priv/cldr",
otp_app: :my_app,
precompile_number_formats: ["¤¤#,##0.##"],
precompile_transliterations: [{:latn, :arab}, {:thai, :latn}],
providers: [Cldr.Number],
generate_docs: true,
force_locale_download: false
end
Otp App Configuration
In the backend configuration example above the :otp_app
key has been defined. This means that Cldr
will look for additional configuration, defined under the key :my_app
with the sub-key MyApp.Cldr
. For example:
# cldr.ex
defmodule MyApp.Cldr do
use Cldr,
otp_app: :my_app,
default_locale: "en",
gettext: MyApp.Gettext,
json_library: Jason,
data_dir: "./priv/cldr",
precompile_number_formats: ["¤¤#,##0.##"],
providers: [Cldr.Number]
end
# config/config.exs
config :my_app, MyApp.Cldr,
# a single locale, for fast compilation in dev / test
locales: ["en"]
# config/production.exs
config :my_app, MyApp.Cldr,
# these will take a while to compile
locales: ["fr", "en", "bs", "si", "ak", "th"],
precompile_transliterations: [{:latn, :arab}, {:thai, :latn}]
Multiple backends can be configured under a single :otp_app
if required.
Global configuration.
In config.exs
a global configuration can be defined under the :ex_cldr
key. Although any valid configuration keys can be used here, only the keys :json_library
, :default_locale
, :default_backend
, :cacertfile
, :data_dir
, :force_locale_download
are considered valid. Other configuration keys may be used to aid migration from Cldr
version 1.x but a deprecation message will be printed during compilation. Here's an example of global configuration:
config :ex_cldr,
default_locale: "en",
default_backend: MyApp.Cldr,
json_library: Jason,
cacertfile: "path/to/cacertfile"
Note that the :json_library
key can only be defined at the global level since it is required during compilation before any backend module is compiled.
On most platforms other than Windows the :cacertfile
will be automatically detected. Any configured :cacertfile
will take precedence on all platforms.
If configuration beyond the keys :default_locale
, :cacertfile
or :json_library
are defined a deprecation warning is printed at compile time noting that configuration should be moved to a backend module.
Configuration Priority
When building the consolidated configuration the following priority applies:
- Consider the global configuration
- Merge the otp_app configuration over the top of the global configuration
- Merge the backend module configuration over the top
Backend Configuration Keys
The configuration keys available for Cldr
are:
default_locale
specifies the default locale to be used for this backend. The default locale in case no other locale has been set is"en-001"
. The default locale calculated as follows:- If set by the
:default_locale
key, then this is the priority - If no
:default_locale
key, then a configuredGettext
default locale for this backend is chosen - If no
:default_locale
key is specified and noGettext
module is configured, or is configured but has no default set, useCldr.default_locale/0
which returns either the default locale configurated inmix.exs
under theex_cldr
key or then the system default locale will is currentlyen-001
- If set by the
locales
: Defines what locales will be configured inCldr
. Only these locales will be available and an exceptionCldr.UnknownLocaleError
will be raised if there is an attempt to use an unknown locale. This is the same behaviour asGettext
. Locales are configured as a list of binaries (strings). For convenience it is possible to use wildcard matching of locales which is particulalry helpful when there are many regional variances of a single language locale. For example, there are over 100 regional variants of the "en" locale in CLDR. A wildcard locale is detected by the presence of.
,[
,*
and+
in the locale string. This locale is then matched using the pattern as aregex
to match against all available locales. The example below will configure all locales that start withen-
and the localefr
.
use Cldr,
default_locale: "en",
locales: ["en-*", "fr"]
There is one additional setting which is
:all
which will configure all 541 locales. This is highly discouraged since it will take many minutes to compile your project and will consume more memory than you really want. This setting is there to aid in running the test suite. Really, don't use this setting.:add_fallback_locales
is a boolean key which whentrue
results in the fallback locales being added for each of the configured locales. The default isfalse
. The reason to set this option totrue
is that some data such as rules based number formats and subdivision data are inherited from their language roots. For example, the localeen-001
is inherited from the localeen
. Localeen-001
does not have any rules based number formats or subdivision data defined for it. However localeen
does. Including the fallback locales maximises the opportunity to resolve localised data.:gettext
: configuresCldr
to use aGettext
module as an additional source of locales you want to configure. SinceGettext
uses the Posix locale name format (locales with an '_' in them) andCldr
uses the Unicode format (a '-' as the subtag separator),Cldr
will transliterate locale names fromGettext
into theCldr
canonical form.:data_dir
: indicates where downloaded locale files will be stored. The default is:code.priv_dir(otp_app)
whereotp_app
is the app defined under the:otp_app
configuration key. If that key is not specified then the:ex_cldr
app is used. It is recommended that an:otp_app
key is specified in your backend module configuration.:precompile_number_formats
: provides a means to have user-defined format strings precompiled at application compile time. This has a performance benefit since precompiled formats execute approximately twice as fast as formats that are not precompiled.:precompile_transliterations
: defines those transliterations between the digits of two different number systems that will be precompiled. The is a list of 2-tuples where each tuple is of the form{from_number_system, to_number_system}
where each number system is expressed as an atom. The available number systems is returned byCldr.Number.System.systems_with_digits/0
. The default is the empty list[]
.:precompile_date_time_formats
: provides a means to have user-defined date, time and date time format strings precompiled at application compile time. This has a performance benefit since precompiled formats execute approximately twice as fast as formats that are not precompiled. These formats are used by ex_cldr_date_times.:precompile_interval_formats
: provides a means to have user-defined interval format strings precompiled at application compile time. This has a performance benefit since precompiled formats execute approximately twice as fast as formats that are not precompiled. These formats are used by ex_cldr_date_times.:providers
: a list of modules that provideCldr
functionality to be compiled into the backend module. See the providers section below.:generate_docs
defines whether or not to generate documentation for the modules built as part of the backend. Since these modules represent the public API forex_cldr
, the default istrue
. Setting this key tofalse
(the atomfalse
, not a falsy value) which prevent the generation of docs for this backend.:supress_warnings
defines whether warnings are logged when a provider module is configured but not available. It also controls whether warnings are logged when a number format is compiled at runtime. Its purpose is to help identify those formats which might best be added to the:precompile_number_formats
configuration. The default isfalse
. Warning are not logged when set totrue
.:force_locale_download
determines whether to always download locale files during compilation. Locale data isex_cldr
version dependent. When a new version ofex_cldr
is installed, no locales are installed and therefore locales are downloaded at compilation time as required. This ensures that the right version of the locale data is always associated with the right version ofex_cldr
. However if locale data is being cached in CI/CD there is some possibility that there can be a version mismatch. Since reproducible builds are important, setting theforce_locale_download: true
in a backend or in global configuration adds additional certainty. The default setting isfalse
thereby retaining compatibility with existing behaviour. The configuration can also be made dependent onmix
environment as shown in this example:
defmodule MyApp.Cldr do
use Cldr,
locales: ["en", "fr"],
default_locale: "en",
force_locale_download: Mix.env() == :prod
end
Providers
The data maintained by CLDR is quite large and not all capabilities are required by all applications. Hence Cldr
has additional optional functionality that can be provided through additional hex
packages. In order to support compile-time additions to a configured backend
, any package can define a provider that will be called at compile time.
The currently known providers and their hex
package names are:
| Hex Package | Provider Module | Comment | | :--------------------- | :----------------- | :--------------------------------------------- | | ex_cldr_numbers | Cldr.Number | Formatting of numbers, currencies | | ex_cldr_lists | Cldr.List | Formatting of lists | | ex_cldr_units | Cldr.Unit | Formatting of SI and Imperial units | | ex_cldr_currency | Cldr.Currency | Currency definitions and localizations | | ex_cldr_territories | Cldr.Territory | Formatting of territory (country) data | | ex_cldr_languages | Cldr.Language | Formatting of language information | | ex_cldr_dates_times | Cldr.DateTime | Formatting of dates, times & datetimes | | ex_cldr_locale_display | Cldr.LocaleDisplay | Localising locale names | | ex_cldr_routes | Cldr.Route | Localized routes and route helpers | | ex_money | Money | Operations on and formatting of a money type | | ex_messages | Cldr.Message | Formatting of ICU-formatted messages |
Any library author can create a provider module by exposing a function called cldr_backend_provider/1
that takes a Cldr.Config
struct as a single parameter. The function should return an AST that is inserted into the backend
module being compiled.
Providers are configured on each backend module under the :providers
key. It must be a list of provider modules. For example:
defmodule MyApp.Cldr do
use Cldr,
locales: ["en", "zh"],
default_locale: "en",
providers: [Cldr.Number, Cldr.List]
end
If :providers is nil
(the default), Cldr
will attempt to configure all of the providers described above if they have been installed as deps
. If you don't wish to invoke any providers, use the empty list []
.
Migrating from Cldr 1.x
- Create a
backend
module by following the configuration instructions - Delete any duplicated global configuration in any
config.exs
files. Only the keys:default_locale
and:json_library
are supported in the global configuration - Update any plugs to configure the desired backend
- Adjust any API calls from
Cldr.some_function
toMyApp.Cldr.some_function
. Or better still, alias your backend module where required. ie.alias MyApp.Cldr, as: Cldr
Downloading Locales
Cldr
can be installed from either github
or from hex.
If installed from github then all 571 locales are installed when the repo is cloned into your application deps.
If installed from hex then only the locales "en", "en-001" and "und" are installed. When you configure additional locales these will be downloaded during application compilation.
Localizing Numbers
The Cldr.Number
module implemented in the ex_cldr_numbers package provides number formatting. The public API for number formatting is MyApp.Cldr.Number.to_string/2
. Some examples:
iex> MyApp.Cldr.Number.to_string 12345
"12,345"
iex> MyApp.Cldr.Number.to_string 12345, locale: "fr"
"12 345"
iex> MyApp.Cldr.Number.to_string 12345, locale: "fr", currency: "USD"
"12 345,00 $US"
iex> MyApp.Cldr.Number.to_string 12345, format: "#E0"
"1.2345E4"
iex(> MyApp.Cldr.Number.to_string 1234, format: :roman
"MCCXXXIV"
iex> MyApp.Cldr.Number.to_string 1234, format: :ordinal
"1,234th"
iex> MyApp.Cldr.Number.to_string 1234, format: :spellout
"one thousand two hundred thirty-four"
See h MyApp.Cldr.Number
and h MyApp.Cldr.Number.to_string
in iex
for further information.
Localizing Lists
The Cldr.List
module provides list formatting and is implemented in the ex_cldr_lists package. The public API for list formatting is Cldr.List.to_string/2
. Some examples:
iex> MyApp.Cldr.List.to_string(["a", "b", "c"], locale: "en")
"a, b, and c"
iex> MyApp.Cldr.List.to_string(["a", "b", "c"], locale: "en", format: :unit_narrow)
"a b c"
iex> MyApp.Cldr.List.to_string(["a", "b", "c"], locale: "fr")
"a, b et c"
See h MyApp.Cldr.List
and h MyApp.Cldr.List.to_string
in iex
for further information.
Localizing Units
The Cldr.Unit
module provides unit localization and is implemented in the ex_cldr_units package. The public API for unit localization is Cldr.Unit.to_string/3
. Some examples:
iex> MyApp.Cldr.Unit.to_string 123, :gallon
"123 gallons"
iex> MyApp.Cldr.Unit.to_string 1234, :gallon, format: :long
"1 thousand gallons"
iex> MyApp.Cldr.Unit.to_string 1234, :gallon, format: :short
"1K gallons"
iex> MyApp.Cldr.Unit.to_string 1234, :megahertz
"1,234 megahertz"
iex> MyApp.Cldr.Unit.available_units
[:acre, :acre_foot, :ampere, :arc_minute, :arc_second, :astronomical_unit, :bit,
:bushel, :byte, :calorie, :carat, :celsius, :centiliter, :centimeter, :century,
:cubic_centimeter, :cubic_foot, :cubic_inch, :cubic_kilometer, :cubic_meter,
:cubic_mile, :cubic_yard, :cup, :cup_metric, :day, :deciliter, :decimeter,
:degree, :fahrenheit, :fathom, :fluid_ounce, :foodcalorie, :foot, :furlong,
:g_force, :gallon, :gallon_imperial, :generic, :gigabit, :gigabyte, :gigahertz,
:gigawatt, :gram, :hectare, :hectoliter, :hectopascal, :hertz, :horsepower,
:hour, :inch, ...]
See h MyApp.Cldr.Unit
and h MyApp.Cldr.Unit.to_string
in iex
for further information.
Localizing Dates
Formatting of relative dates and date times is supported in the Cldr.DateTime.Relative
module implemented in the ex_cldr_dates_times package. The public API is MyApp.Cldr.DateTime.to_string/2
and MyApp.Cldr.DateTime.Relative.to_string/2
. Some examples:
iex> MyApp.Cldr.Date.to_string Date.utc_today()
{:ok, "Aug 18, 2017"}
iex> MyApp.Cldr.Time.to_string Time.utc_now
{:ok, "11:38:55 AM"}
iex> MyApp.Cldr.DateTime.to_string DateTime.utc_now
{:ok, "Aug 18, 2017, 11:39:08 AM"}
iex> MyApp.Cldr.DateTime.Relative.to_string 1, unit: :day, format: :narrow
{:ok, "tomorrow"}
iex> MyApp.Cldr.DateTime.Relative.to_string(1, unit: :day, locale: "fr")
"demain"
iex> MyApp.Cldr.DateTime.Relative.to_string(1, unit: :day, format: :narrow)
"tomorrow"
iex> MyApp.Cldr.DateTime.Relative.to_string(1234, unit: :year)
"in 1,234 years"
iex> MyApp.Cldr.DateTime.Relative.to_string(1234, unit: :year, locale: "fr")
"dans 1 234 ans"
Gettext Pluralization
gettext allows for user-defined plural forms modules to be configured for a gettext backend.
To define a plural forms module that uses CLDR plural rules
create a new module and then use Cldr.Gettext.Plural
. For example:
defmodule MyApp.Gettext.Plural do
use Cldr.Gettext.Plural, cldr_backend: MyApp.Cldr
end
This module can then be used in the configuration of a gettext
backend.
For example:
defmodule MyApp.Gettext do
use Gettext, plural_forms: MyApp.Gettext.Plural
end
Note that MyApp.Gettext.Plural
does not guarantee to return the same plural index
as Gettext
's own pluralization engine which can introduce some compatibility issues if you plan to mix plural engines. See Cldr.Gettext.Plural
for more information.
About Language Tags
Note that ex_cldr
defines locale strings according to the IETF standard as defined in RFC5646. ex_cldr
also implements the u
extension as defined in RFC6067 and the t
extension defined in RFC6497. This is also the standard used by W3C.
The IETF standard is slightly different to the ISO/IEC 15897 standard used by Posix-based systems; primarily in that ISO 15897 uses a "_" separator whereas IETF and W3C use "-".
Locale string are case insensitive but there are common conventions:
- Language codes are lower-cased
- Territory codes are upper-cased
- Script names are capital-cased
- All other subtags are lower-cased
Sigil_l
As of ex_cldr
version 2.23.0, a sigil is available to simplify creating t:Cldr.LanguageTag
structs. Usage is:
iex> import Cldr.LanguageTag.Sigil
Cldr.LanguageTag.Sigil
# Returns a locale that is valid and known to
# the default backend module
iex> ~l(en-US)
#Cldr.LanguageTag<en-US [validated]>
# Same, but specifying the backend module
# MyApp.Cldr specifically
iex> ~l(en-US|MyApp.Cldr)
#Cldr.LanguageTag<en-US [validated]>
# The `u` flag will parse and validate
# the language tag but it may not be known
# as a configured locale
iex> ~l(zh)u
#Cldr.LanguageTag<zh [canonical]>
# Language tags can convey a lot more information
# than might be initially expected!
iex> ~l(en-u-ca-ethiopic-cu-aud-sd-gbsct-t-d0-lower-k0-extended-m0-ungegn-x-ux)
#Cldr.LanguageTag<en-t-d0-lower-k0-extended-m0-ungegn-u-ca-ethiopic-cu-aud-sd-gbsct-x-ux [validated]>
Locale extensions
Unicode defines the U extension which support defining the requested treatment of CLDR data formats. For example, a locale name can configure the requested:
- calendar to be used for dates
- collation
- currency
- currency format
- number system
- first day of the week
- 12-hour or 24-hour time
- time zone
- and many other items
For example, the following locale name will request the use of the timezone Australia/Sydney
,
and request the use of accounting
format when formatting currencies:
iex> MyApp.Cldr.validate_locale "en-AU-u-tz-ausyd-cf-account"
{:ok,
%Cldr.LanguageTag{
canonical_locale_name: "en-Latn-AU",
cldr_locale_name: "en-AU",
extensions: %{},
gettext_locale_name: "en",
language: "en",
language_subtags: [],
language_variants: nil,
locale: %Cldr.LanguageTag.U{cf: :account, timezone: "Australia/Sydney"},
private_use: [],
rbnf_locale_name: "en",
requested_locale_name: "en-AU",
script: :Latn,
territory: :AU,
transform: %{}
}}
The implementation of these extensions is governed by each library in the ex_cldr
family. As of January 2020, ex_cldr_numbers version 2.10 implements the following U
extension keys:
cf
(currency format)cu
(currency)nu
(number system)
Other libraries in the family will progressively implement other extension keys.
Notes
- A language code is an ISO-3166 language code.
- Potentially one or more modifiers separated by
-
(dash), not a_
. (underscore). If you configure aGettext
module thenCldr
will transliterateGettext
's_
into-
for compatibility. - Typically the modifier is a territory code. This is commonly a two-letter uppercase combination. For example
pt-PT
is the locale referring to Portuguese as used in Portugal. - In
ex_cldr
a locale name is always abinary
and never anatom
. Internally a locale is parsed and stored as at:Cldr.LanguageTag
struct. - The locales known to
ex_cldr
can be retrieved byCldr.known_locale_names/1
to get the locales known to this configuration ofex_cldr
andCldr.all_locale_names/0
to get the locales available in the CLDR data repository.
Developing ex_cldr
See the file DEVELOPMENT.md
in the github repository.
Testing
Tests cover the full 571 locales defined in CLDR. Since Cldr
attempts to maximize the work done at compile time in order to minimize runtime execution, the compilation phase for tests is several minutes.
Tests are run on Elixir 1.11 and later. ex_cldr
may not run on Elixir versions before 1.11.