Generate an elm translation module from json language files.
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Elm i18n Gen (JSON language file to Elm Functions Generator)

npm version

This tool lets you generate elm functions from JSON translation files.

This tool is for you if ...

  • you store your translations in the JSON format
  • you want to be able to switch languages during runtime
  • you want to use your translations in your Elm app

(if you need other formats than JSON go to the end of this README to find a link to a different tool)

Why was this tool created?

The company I work for stores all their translation files in JSON and also depends on this format, for collaboration with a third party translation service. So storing the translations in Elm directly was not an option for us. We still didn't want to miss out on the Elm goodness. Thus, this i18n module generator was born.

How to use?

Warning: This module currently only supports placeholders in translations that are surrounded by {{ ... }}.

For every translation string one elm function will be generated. Translations without placeholders will be transformed to a function with this signature.

Lang -> String

With Placeholders the signature will look more like this: (for one placeholder):

Lang -> String -> String

Generating the Translation elm module

Install via npm.

npm install -g elm-i18n-gen

Then run it from the command line.

elm-i18n-gen path/to/localeFolder path/to/output/Translations.elm

This currently assumes that you have a single folder that contains all your JSON translation files that are name *.<lang>.json one the same level like so:

  |- mytranslation.en.json

Imagine the translation files look like this:

  "hello": "Hello",
  "gooddaySalute": "Good Day {{name}} {{assi}}",
  "tigers": {
    "roar": "Roar!"

in english and in german

  "hello": "Hallo",
  "gooddaySalute": "Guten Tag {{name}} {{assi}}",
  "tigers": {
    "roar": "Brüll!"

This will generate a Translations.elm file with the follwing content.

module Translations exposing (..)

type Lang
  =  De
  |  En

getLnFromCode: String -> Lang
getLnFromCode code =
   case code of
      "de" -> De
      "en" -> En
      _ -> En

hello: Lang -> String
hello lang  =
  case lang of
      De -> "Hallo"
      En -> "Hello"

gooddaySalute: Lang -> String -> String -> String
gooddaySalute lang str0 str1 =
  case lang of
      De -> "Guten Tag " ++ str0 ++ " " ++ str1 ++ ""
      En -> "Good Day " ++ str0 ++ " " ++ str1 ++ ""

tigersRoar: Lang -> String
tigersRoar lang  =
  case lang of
      De -> "Brüll!"
      En -> "Roar!"

Using the Translations module

Import the generated module in your elm code like this.

import Translations

Initialize your Model with a language, it is a union type generated from your language files:

initialModel: Model
initialModel =
  { tigers: List Tiger
  , lang: Translations.En -- <---- add language type

Then in your view function do this:

view: Model -> Html Msg
view model = div [] [text (Translations.hello model.lang)]

Future Features

This is a list of TODOs that I plan to implement. Pull Requests are also welcome. Just contact me if you want to contribute.

  • Clean up
  • Use command line arguments to configure different placeholder separator (__xxx__, {{{xxx}}}, etc)
  • Port the generating logic to elm in an elm worker and only use node for file IO.


If you find bugs are need additional features please open an issue or contact me to discuss ideas. If you want to write code check out the repo and add your code. Make sure to run the test with npm test before and add tests wherever it makes sense. Submit a PR against the master branch.


This project was inspired by IOSphere/elm-i18n, namely the idea of representing translation strings as constants or functions. But it is adapted to fit other needs. It differs in the fact that elm-i18n-gen generates a single elm module from multiple JSON files vs iosphere/elm-i18n, which stores its translations in elm directly and generates other formats from it.