Orphan Instances with GHC 6.8
ahey at iee.org
Wed Oct 17 13:32:45 EDT 2007
Simon Peyton-Jones wrote:
> What you say rings no bells. I don't see how to make progress without more info.
> Perhaps show the module that elicits the unexpected orphan message?
The problem I'm having is with collections-package..
but, it's complicated by the fact that..
1- The code I'm working on is my local repository (which amongst
other things) has some changes in it to get it to compile
with 6.8 (experimentally), so is not quite the same.
2- I can't get exactly the same code to compile with the different
3- Every experiment I try takes a long time because the collections
package takes a long time to build.
4- I'm a bit busy today :-)
So I'm afraid I can't provide a small demo of the problem because
I'm having a hard time reproducing it consistently. But I'll
try to get to produce some kind of reproducible (but not necessarily
small :-) test case soon. Or else just report this as a false alarm
caused by me doing something silly :-)
So maybe for the time being you should forget I mentioned this as
I don't want to waste anybody's time.
> | -----Original Message-----
> | From: Adrian Hey [mailto:ahey at iee.org]
> | Sent: 17 October 2007 17:04
> | To: glasgow-haskell-users at haskell.org; Simon Peyton-Jones
> | Subject: Re: Orphan Instances with GHC 6.8
> | Hello again,
> | Adrian Hey wrote:
> | > Hello Folks,
> | >
> | > One thing different from 6.6 and 6.8 is I find that with -Wall
> | > I get a lot more warnings about orphan instances, even if the
> | > code has not changed.
> | >
> | > Has the definition of what an Orphan instance is changed?
> | >
> | > Or is this a bug? If so, is the bug in 6.6 or 6.8?
> | >
> | > I can make them go away with the -fno-warn-orphans flag,
> | > but I'm still curious as to why I didn't have to do this before.
> | Sorry, this situation seems more complex than this. I can't quite
> | figure out whats going on, in fact this but it may to be related
> | to some other change I've made in the code to get since 6.8.
> | The strange thing (to me) is that if I take exactly the same module
> | and use it in 2 different packages (which are compiled with the same
> | ghc options AFAIK), one gives me the orphan warning and one doesn't.
> | Does that make sense? (I.E. Is "Orphanness" somehow context dependent?)
> | Thanks
> | --
> | Adrian Hey
More information about the Glasgow-haskell-users