Top-level binding groups

[Jan Rochel]

Hello,

In my current efforts of generalising the static argument transformation
(SAT) I am confronted with a problem concerning the core language. It is
about top-level bindings and how they are organised in (Rec/NonRec)
binding groups. I was assuming that a non-exported top-level binding
defined in one binding group could never be used from outside of that
group. When compiling GHC, however, I came across (few) cases where this
rule was broken.

So, what can I expect of top-level binding groups?
[ ] bindings cannot be used from another group
[ ] only exported bindings can be used from another group
[ ] mutual recursion may only occur within one group
[ ] none of the above
[ ] _____________________________________________________

Thanks in advance
Jan