I initiated an effort to write a tutorial on using GTK in ATS:
http://www.ats-lang.org/DOCUMENT/ATS2GTK/HTML/book1.html
If doing it alone, I could only do this very very slowly.
If you are interested in contributing, I will be happy to merge your
contribution
into the API for GTK in ATS and/or the tutorial.
See:
https://github.com/githwxi/ATS-Postiats/tree/master/contrib/GTK
Cheers,
–Hongwei