Hi, the RTS continues to use the libc as usual. Maybe in some far future we could use a stripped down libc but for now I want to use GHC and Linux unmodified so that the system stays easy to test.
Then in a probably far future I would like to use it to try different (crazy) things. For instance configuring the whole system with type-checked Haskell code (similar to XMonad configuration but for the whole system); provide a better terminal-like interface/protocol replacing stdin/stdout/stderr/term ioctls; generalize Linux sandboxing to all applications (filter syscalls, use namespaces, disk quota, etc.) and manage per-application permissions; etc.
The closest approach is Android which also uses the Linux kernel but doesn't provide a Unix interface to applications.
* GNU tools (ls, tail, bash, gdb, etc.)
* OS infrastructure (Systemd, Xorg/Wayland, etc.; probably not Mesa/DRM though as he says he doesn't want to do drivers)
* Desktop environments (KDE, GNOME, etc.)
* ... random other packages like Nethack ...
Honestly the goal seems kind of insane, like Don Quixote trying to reach the unreachable star. But I guess it's good advertising for the consulting work, and of course research projects generate useful side benefits. And writing software in Haskell is fun, so they just might succeed :-)