https://3e8.org/pub/scheme/doc/p1-armstrong.pdf
When you don't need a full fledged window manager but just want to display a sensor value or a couple of push buttons and a slider on a 5" screen, try this all erlang graphics library.
With erlang you get:
- Soft realtime.
- Concurrency.
- Hot code loading.
- BQ Aquaris E4.5 with Ubunty Touch with Mir @UBports
- Mac OSX
- Raspbian on Raspberry Pi
Draw custom widgets