Fuzzy translation key merging with Gettext

Gettext is a great tool for i18n in elixir. It provides a mix task for extracting translation keys from your code. The translation keys (or message ids) are natural language and look like this:

gettext("Hi, Welcome to Tilex!")

After running mix gettext.extract && mix gettext.merge, an already translated Italian locale file would look like:

msgid "Hi, Welcome to Tilex!"
msgstr "Italian version of Welcome!"

There's a chance that the natural language key (which also serves as the default string) will change.

If it changes just a little bit then the Italian locale file will look like:

#, fuzzy
msgid "Hi, Welcome to Tilex!!"
msgstr "Italian version of Welcome!"

It gets marked as #, fuzzy, and the new msgid replaced the old msgid.

Gettext determines how big of a change will constitute a fuzzy match with String.jaro_distance.

iex> String.jaro_distance("something", "nothing")
0.8412698412698413
iex> String.jaro_distance("peanuts", "bandersnatch")
0.576984126984127

The higher the number the closer the match. fuzzy_threshold is the configuration that determines whether a msgid is fuzzy or not and the default for fuzzy_threshold is 0.8, set here.