Developing Web Apps with Haskell and Yesod, 2nd Edition

Chapter 16. Internationalization

Users expect our software to speak their language. Unfortunately for us, there will likely be more than one language involved. While doing simple string replacement isn’t too involved, correctly dealing with all the grammar issues can be tricky. After all, who wants to see “List 1 file(s)” from a program output?

But a real i18n solution needs to do more than just provide a means of achieving the correct output. It needs to make this process relatively error-proof, and easy for both the programmer and the translator. Yesod’s answer to the problem gives you:

• Intelligent guessing of the user’s desired language based on request headers, with the ability to override.

• A simple syntax for giving translations that requires no Haskell knowledge. (After all, most translators aren’t programmers.)

• The ability to bring in the full power of Haskell for tricky grammar issues as necessary, along with a default selection of helper functions to cover most needs.

• Absolutely no issues at all with word order.

Synopsis

-- @messages/en.msg
Hello: Hello
EnterItemCount: I would like to buy:
Purchase: Purchase
ItemCount count@Int: You have purchased #{showInt count}
                     #{plural count "item" "items"}.
SwitchLanguage: Switch language to:
Switch: Switch

-- @messages/he.msg
Hello: שלום
EnterItemCount: אני רוצה לקנות:
Purchase: קנה
ItemCount count: קנית #{showInt count} #{plural count "דבר" "דברים"}.
SwitchLanguage: החלף שפה ל:
Switch: החלף

{-# LANGUAGE MultiParamTypeClasses ...