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elixir-cldr
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Description

Elixir implementation of CLDR/ICU

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Getting Started with Cldr

Build Status Hex.pm Hex.pm Hex.pm Hex.pm

Introduction

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 of numbers, lists, currencies, calendars, units of measure and dates/times. As of November 2020 and
ex_cldr
Version 2.18.0,
Cldr
is based upon CLDR version 38.0.0.

The first step is to define a module that will host the desired

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:
@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:

  • 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

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:
  • Cldr.Config.get_locale/2
    which returns a map of all the CLDR data known to
    Cldr
    . Since this data is read from a file, parsed and then formatted it is a function that should be used with care due to the material performance implications.
    Cldr
    uses this function during compilation to build functions that return the relevant data with higher performance and these functions are to be preferred over the use of
    Cldr.Config.get_locale/2
    .

Use this package when you have a requirement to...

  • Support multiple languages and locales in your application

  • Need to support formatting numbers, dates, times, date-times, units and lists in one language or many

  • 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 1.6 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, "~> 2.0"},
    # 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
and the JSON library from hex:
elixir
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 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. 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
,
:cacertfile
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",
  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.

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}],
    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 configuration 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:

  • 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 configured
      Gettext
      default locale for this backend is chosen
    • If no
      :default_locale
      key is specified and no
      Gettext
      module is configured, or is configured but has no default set, use
      Cldr.default_locale/0
      which returns either the default locale configurated in
      mix.exs
      under the
      ex_cldr
      key or then the system default locale will is currently
      en-001
  • locales
    : Defines what locales will be configured in
    Cldr
    . Only these locales will be available and an exception
    Cldr.UnknownLocaleError
    will be raised if there is an attempt to use an unknown locale. This is the same behaviour as
    Gettext
    . Locales are configured as a list of binaries (strings). For convenince 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 a
    regex
    to match against all available locales. The example below will configure all locales that start with
    en-
    and the locale
    fr
    .
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.
  • :gettext
    : configures
    Cldr
    to use a
    Gettext
    module as an additional source of locales you want to configure. Since
    Gettext
    uses the Posix locale name format (locales with an '_' in them) and
    Cldr
    uses the Unicode format (a '-' as the subtag separator),
    Cldr
    will transliterate locale names from
    Gettext
    into the
    Cldr
    canonical form.
  • :data_dir
    : indicates where downloaded locale files will be stored. The default is
    :code.priv_dir(otp_app)
    where
    otp_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 by
    Cldr.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 excldrdate_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 excldrdate_times.
  • :providers
    : a list of modules that provide
    Cldr
    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 for
    ex_cldr
    , the default is
    true
    . Setting this key to
    false
    (the atom
    false
    , 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 is
    false
    . Warning are not logged when set to
    true
    .
  • :force_locale_download
    determines whether to always download locale files during compilation. Locale data is
    ex_cldr
    version dependent. When a new version of
    ex_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 of
    ex_cldr
    . However if locale data is being cached in CI/CD there is some possibility that there can be a version mismatch. Since reproducable builds are important, setting the
    force_locale_download: true
    in a backend or in global configuration adds additional certainty. The default setting is
    false
    thereby retaining compatibility with existing behaviour. The configuration can also be made dependent on
    mix
    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 | | :------------------- | :---------------- | :------------------------------------------ | | excldrnumbers | Cldr.Number | Formatting of numbers, currencies | | excldrlists | Cldr.List | Formatting of lists | | excldrunits | Cldr.Unit | Formatting of SI and Imperial units | | excldrterritories | Cldr.Territory | Formatting of territory (country) data | | excldrlanguages | Cldr.Language | Formatting of language information | | excldrdatestimes | Cldr.DateTime | Formatting of dates, times & datetimes | | exmoney | Money | Operations 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:
elixir
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

  1. Create a
    backend
    module by following the configuration instructions
  2. Delete any duplicated global configuration in any
    config.exs
    files. Only the keys
    :default_locale
    and
    :json_library
    are supported in the global configuration
  3. Update any plugs to configure the desired backend
  4. Adjust any API calls from
    Cldr.some_function
    to
    MyApp.Cldr.some_function
    . Or better still, alias your backend module where required. ie.
    alias MyApp.Cldr, as: Cldr

Downloading Configured Locales

Cldr
can be installed from either github or from hex.
  • If installed from github then all 541 locales are installed when the repo is cloned into your application deps.

  • If installed from hex then only the locales "en", "en-001" and "root" are installed. When you configure additional locales these will be downloaded during application compilation.

Localizing and Formatting Numbers

The

Cldr.Number
module implemented in the excldrnumbers package provides number formatting. The public API for number formatting is
MyApp.Cldr.Number.to_string/2
. Some examples: ```elixir 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.tostring 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 excldrlists package. The public API for list formating is
Cldr.List.to_string/2
. Some examples: ```elixir iex> MyApp.Cldr.List.to_string(["a", "b", "c"], locale: "en") "a, b, and c"

iex> MyApp.Cldr.List.tostring(["a", "b", "c"], locale: "en", format: :unitnarrow) "a b c"

iex> MyApp.Cldr.List.tostring(["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 excldrunits package. The public API for unit localization is
Cldr.Unit.to_string/3
. Some examples: ```elixir 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.availableunits [:acre, :acrefoot, :ampere, :arcminute, :arcsecond, :astronomicalunit, :bit, :bushel, :byte, :calorie, :carat, :celsius, :centiliter, :centimeter, :century, :cubiccentimeter, :cubicfoot, :cubicinch, :cubickilometer, :cubicmeter, :cubicmile, :cubicyard, :cup, :cupmetric, :day, :deciliter, :decimeter, :degree, :fahrenheit, :fathom, :fluidounce, :foodcalorie, :foot, :furlong, :gforce, :gallon, :gallonimperial, :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 excldrdates_times package. The public API is
MyApp.Cldr.DateTime.to_string/2
and
MyApp.Cldr.DateTime.Relative.to_string/2
. Some examples: ```elixir iex> MyApp.Cldr.Date.tostring Date.utctoday() {:ok, "Aug 18, 2017"}

iex> MyApp.Cldr.Time.tostring Time.utcnow {:ok, "11:38:55 AM"}

iex> MyApp.Cldr.DateTime.tostring DateTime.utcnow {: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:
elixir
    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:
  • Cldr.Plug.AcceptLanguage
    which will parse an
    accept-language
    header and resolve the best matched and configured
    Cldr
    locale. The result is stored in
    conn.private[:cldr_locale]
    which is also returned by
    Cldr.Plug.AcceptLanguage.get_cldr_locale/1
    .
  • Cldr.Plug.SetLocale
    which will look for a locale in the several places and then call
    Cldr.put_locale/2
    and
    Gettext.put_locale/2
    if configured so to do. Finally, The result is stored in
    conn.private[:cldr_locale]
    which is then available through
    Cldr.Plug.SetLocale.get_cldr_locale/1
    . The plug will look for a locale in the following locations depending on the plug configuration:
    • path_params
    • query_params
    • body_params
    • cookies
    • accept-language
      header
    • the
      session

See

Cldr.Plug.SetLocale
for a description of how to configure the plug.

In addition, note that when migrating from

ex_cldr
1.x versions, a backend needs to be configured for both plugs. In the simplest case an example would be: ```elixir plug Cldr.Plug.SetLocale, apps: [:cldr], cldr: MyApp.Cldr

plug Cldr.Plug.AcceptLanguage, cldr_backend: MyApp.Cldr ```

Using Cldr.Plug.SetLocale without Phoenix

If you are using

Cldr.Plug.SetLocale
without Phoenix and you plan to use
:path_param
to identify the locale of a request then
Cldr.Plug.SetLocale
must be configured after
plug :match
and before
plug :dispatch
. For example: ```elixir defmodule MyRouter do use Plug.Router

plug :match

plug Cldr.Plug.SetLocale, apps: [:cldr, :gettext], from: [:path, :query], gettext: MyApp.Gettext, cldr: MyApp.Cldr

plug :dispatch

get "/hello/:locale" do send_resp(conn, 200, "world") end end ```

Using Cldr.Plug.SetLocale with Phoenix

If you are using

Cldr.Plug.SetLocale
with Phoenix and you plan to use the
:path_param
to identify the locale of a request then
Cldr.Plug.SetLocale
must be configured in the router module, not in the endpoint module. This is because
conn.path_params
has not yet been populated in the endpoint. For example: ```elixir defmodule MyAppWeb.Router do use MyAppWeb, :router

pipeline :browser do plug :accepts, ["html"] plug :fetchsession plug Cldr.Plug.SetLocale, apps: [:cldr, :gettext], from: [:path, :query], gettext: MyApp.Gettext, cldr: MyApp.Cldr plug :fetchflash plug :protectfromforgery plug :putsecurebrowser_headers end

scope "/:locale", HelloWeb do pipe_through :browser

get "/", PageController, :index

end

end ```

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:

  • Language codes are lower-cased
  • Territory codes are upper-cased
  • Script names are capital-cased

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:
elixir
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_variant: nil,
   locale: %{currency_format: :accounting, 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, excldrnumbers 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 ISO3166 language code.
  • Potentially one or more modifiers separated by
    -
    (dash), not a
    _
    . (underscore). If you configure a
    Gettext
    module then
    Cldr
    will transliterate
    Gettext
    '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 Portugese as used in Portugal.
  • In
    Cldr
    a locale name is always a
    binary
    and never an
    atom
    . Internally a locale is parsed and stored as a
    Cldr.LanguageTag
    struct.
  • The locales known to
    Cldr
    can be retrieved by
    Cldr.known_locale_names/1
    to get the locales known to this configuration of
    Cldr
    and
    Cldr.all_locale_names/0
    to get the locales available in the CLDR data repository.

Testing

Tests cover the full 566 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 1.6 and later.

Cldr
will not run on Elixir versions before 1.6.

Developing ex_cldr

See the file

DEVELOPMENT.md

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