proposal #2254: have Control.Arrow re-export (>>>) and (<<<)

Simon Peyton-Jones simonpj at
Tue May 6 04:58:11 EDT 2008

| This is actually not what I was hinting at, I'll see if I can
| reproduce the bug I experienced. The basic idea behind it was that
| module A in package a defines some type class, with member function
| foo. Modules B and C in packages b and c separately import A and
| create instances of that class, and reexports foo. Then module D in
| package D cannot import both B and C and use foo, it will give an
| "Ambiguous occurence" error. I tried reproducing this in a simpler
| setting, with ABCD all in one package, but the error wouldn't appear.
| I hope I wasn't imagining things (or rather, it would be good if I was
| :-)). There may have been some qualified imports involved too...

That certainly sounds like a bug.  If you can reproduce it, please file it as such.


More information about the Libraries mailing list