Elm 0.19: details of what's new, how to install/upgrade, reading list

This morning, my Twitter timeline was abuzz with exciting news: Elm 0.19 has been released!

The official announcement focused on the big ticket items: impressive reductions in the size of the generated JavaScript and no less impressive improvements in compilation speed. Those are very good things, but I wanted to provide a more comprehensive list (including some stuff that didn't make it into the release notes either).

Changes

Language changes

Nothing major has been added but a few things h...