Getting Started with Cldr 2.0

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Getting Started

Cldr is an Elixir library for the Unicode Consortium’sCommon Locale Data Repository (CLDR). The intentions of CLDR, and this library, is to simplify the locale specific formatting of numbers, lists, currencies, calendars, units of measure and dates/times. As of October 18th 2018 and Version 1.8.0, Cldr is based upon CLDR version 34.0.0.

The first step is to define a module that will host the desired Cldr configuration and the functions that servce the public API. This module is referred to in this documentation as a backend module. For example:

@doc """
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.
"""
defmodule MyApp.Cldr do
  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:

To access the raw Cldr data for a locale the Cldr.Config module is available. Note that the functions in Cldr.Config are typically used by library authors. The most useful function is:

Use this package when you have a requirement to…

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

Installation

Add ex_cldr as a dependency to your mix project:

defp deps do
  [
    {:ex_cldr, "~> 2.0"},
    # Posion 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 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:

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 537 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. However configuration can also be defined in other ways:

Global configuration.

In mix.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 and default_locale 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",
   json_library: Jason,

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.

Global configuration most closely approximates the configuration methods in Cldr version 1.x and therefore remains supported to ease migration only.

If configuration beyond the keys :default_locale or :json_library are defined a deprecation warning is printed at compile time noting that configuration should be moved to a backend module.

Backend Module Configuration

The preferred configuration method is to define the configuration in the backend module. 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"],
     gettext: MyApp.Gettext,
     data_dir: "./priv/cldr",
     otp_app: :my_app
     precompile_number_formats: ["¤¤#,##0.##"],
     precompile_transliterations: [{:latn, :arab}, {:thai, :latn}]
  end

Otp App Configuration

In the backend configuration example above the :otp_app key has been defined. This means that conifguration for Cldr has been defined in mix.exs under the key :my_app with the sub-key MyApp.Cldr. For example:

 defmodule MyApp.Cldr do
   use Cldr, otp_app: :my_app
 end

 # In mix.exs
 config :my_app, MyApp.Cldr,
   default_locale: "en",
   locales: ["fr", "en", "bs", "si", "ak", "th"],
   gettext: MyApp.Gettext,
   data_dir: "./priv/cldr",
   precompile_number_formats: ["¤¤#,##0.##"],
   precompile_transliterations: [{:latn, :arab}, {:thai, :latn}]

Multiple backends can be configured under a single :otp_app if required.

Configuration Priority

When building the consolidated configuration the following priority applies:

Configuration Keys

The configuration keys available for Cldr are:

use Cldr,
  default_locale: "en",
  locales: ["en-*", "fr"]

Downloading Configured Locales

Cldr can be installed from either github or from hex.

Localizing and Formatting 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 formating 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, Times and DateTimes

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 Backend Pluralization Support

There is an experimental plurals module for Gettext called Cldr.Gettext.Plural. It is configured in Gettext by:

defmodule MyApp.Gettext do
  use Gettext, plural_forms: Cldr.Gettext.Plural
end

Cldr.Gettext.Plural will fall back to Gettext pluralisation if the locale is not known to Cldr. This module is only compiled if Gettext is configured as a dependency in your project.

Note that Cldr.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.

Plugs

Cldr provides two plugs to aid integration into an HTTP workflow. These two plugs are:

About Language Tags and Locale strings

Note that Cldr defines locale strings according to the IETF standard as defined in RFC5646. 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:

Notes

Testing

Tests cover the full 537 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 1.5 and later. Cldr will not run on Elixir versions before 1.5.

Updating the CDLR data repository if installing from Github

The CLDR data is maintained in JSON format by the Unicode Consortium. The appropriate content is maintained as submodules in the data directory of this Cldr repository.

If this repo has just been cloned then first of all you will need to initialize and retrieve the submodules:

git submodule update --init data/*

When CLDR releases new data then the submodules in this repo also need to be updated. To update the CDLR data, git pull each of the submodules. For example:

git submodule -q foreach git pull -q origin master

From time-to-time ISO will update the repository of ISO3166 language codes. Ensure you have the latest version downloaded:

mix cldr.download.iso_currency

The file pluralRanges.xml needs to be updated with each release and stored in the ./data directory. This is manually extracted from the core.zip file downloaded from the CLDR repository. It will be transformed into a json version during the next phase, consolidation.

After updating the respository, the locales need to be consolidated into the format used by Cldr. This is done by:

mix cldr.consolidate

Then you will need to regenerate the language_tags.ebin file by executing the following. Note that MIX_ENV=test is essential since thats how we guarantee all locales are configured.

MIX_ENV=test mix cldr.generate_language_tags