Keith Lazuka and AJ Alt from Microsoft share their experience writing the amazing [Elm language support package](https://klazuka.github.io/intellij-elm/) for the IntelliJ family of integrated development environments. Thank you to our sponsors, [Ellie](https://ellie-app.com), [Culture Amp](https://cultureamp.com/jobs) and [Joel Clermont](https://twitter.com/jclermont). Special thanks to Xavier Ho ([@Xavier_Ho](https://twitter.com/Xavier_Ho)) for editing and production of this episode! **Recording date:** 23 February 2019 ## Guests - Keith Lazuka ([@klazuka](https://twitter.com/@klazuka)) - AJ Alt ([@ajalt on Medium](https://medium.com/@ajalt)) ## Show Notes 00:00:00 **Introduction** 00:01:37 **Guest intro** - [intellij-elm](https://klazuka.github.io/intellij-elm/) - [elm-hot](https://github.com/klazuka/elm-hot) 00:02:45 **Project beginnings** 00:07:10 **About IntelliJ** 00:08:04 **Elm at Microsoft** 00:09:20 **Writing IntelliJ plugins with Kotlin** 00:13:34 **Parsing Elm to produce an Abstract Syntax Tree (AST)** 00:16:22 **So many features!** 00:18:56 **Type inference** 00:19:55 **How do you decide what features to build?** 00:20:44 **Tidying up dead code and imports since Elm 0.19** 00:23:03 **Supporting both Elm 0.18 and Elm 0.19** 00:27:25 **Parsing partial Elm programs with errors** 00:30:38 **Language servers and multi-editor support** 00:32:57 **Saving on scrolling** 00:34:28 **Effortless refactoring** 00:36:19 **Extensible records** 00:37:43 **Test-driven development & BNF grammar** 00:38:39 **How do you split work?** 00:40:42 **Outro**