fail: <<loop>>

[Peter White]

No, I am not utterly stuck, because the workaround is to use my own instance
of show instead of the derived instance. BTW, in the same program, I have
defined my own instance of Ord instead of using the derived instance,
because the derived instance of Ord also causes fail: <<loop>>. Anyone out
there in Haskell land seeing a "fail: <<loop>>" might check into derived
instances of Ord, Show, ...

-----Original Message-----
From: Simon Peyton-Jones [mailto:simonpj at microsoft.com]
Sent: Wednesday, March 27, 2002 4:04 AM
To: Peter White; glasgow-haskell-bugs at haskell.org
Subject: RE: fail: <<loop>>


Peter,

This is a most excellent bug.  Thank you.  It turns out to be an
obscure interaction in the context-simplication machinery between
functional dependencies and superclasses.

I need to think about how to fix it, and I'm buried in reviewing right
now, so I hope you are not utterly stuck.

Simon

| -----Original Message-----
| From: Peter White [mailto:wpd at uswest.net]
| Sent: 25 March 2002 21:38
| To: glasgow-haskell-bugs at haskell.org
| Subject: fail: <<loop>>
|
|
| Attached is a program that produces fail: <<loop>> when I
| execute it. I am using the derived instance of Show for the
| type LinuxObjectId. When I replace this with my own Show
| instance (currently commented out in the source code), then
| the program executes to completion. I am using Ghc version
| 5.03.20020204
|
|
|
|