I'm an author Ajhc Haskell compiler http://ajhc.metasepi.org/.
Now Haskell code compiled with Ajhc is running on ChibiOS/RT!
https://github.com/metasepi/chibios-arafura
Enjoy!
Do you see any real advantages by using Haskell on an M4 over C or is it just playing around / of educational purpose?