I18n for elm application

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I currently have great success by using the simple technique described in https://www.gizra.com/content/elm-i18n-type-safety/ (which I found by following the advice in https://github.com/lukewestby/elm-i18n).

What is great with it is that you can’t forget to translate things and you can also have localization of any type, for example date formats, 12/24 hour format, number formats, etc.

I have something like this:

module I10n exposing (Language(..), TranslationId(..), i10n)

import FormatNumber exposing (format)
import FormatNumber.Locales exposing (frenchLocale, usLocale)
import Time.DateTime as DateTime exposing (DateTime)

type Language
    = English
    | French

type TranslationId
    = Hello
    | Date DateTime
    | FloatValue Float


i10n : Language -> TranslationId -> String
i10n lang id =
    case lang of
        English ->
            case id of
                Hello ->
                    "Hello"

                Date datetime ->
                    String.concat
                        [ leadingZero (DateTime.month datetime)
                        , "/"
                        , leadingZero (DateTime.day datetime)
                        , "/"
                        , toString (DateTime.year datetime)
                        ]

                FloatValue value ->
                    format { usLocale | decimals = 2 } value

        French ->
            case id of
                Hello ->
                    "Bonjour"

                Date datetime ->
                    String.concat
                        [ leadingZero (DateTime.day datetime)
                        , "/"
                        , leadingZero (DateTime.month datetime)
                        , "/"
                        , toString (DateTime.year datetime)
                        ]

                FloatValue value ->
                    format { frenchLocale | decimals = 2 } value

For now, I am really satisfied by this method, but I don’t have that many strings in my app, and I don’t mind having all translations embedded, so YMMV. I guess translated strings could still be loaded through HTTP if needed.

Edit: they also have a script to translate i18n key/value JSON files to Elm types:

https://github.com/dragonwasrobot/i18n-to-elm

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