GHC 6.4 release candidates available

Keean Schupke k.schupke at
Wed Mar 2 12:19:59 EST 2005

In the past having:

{-# OPTIONS -fallow-overlapping-instances #-}

in a module was enough to get ghci to allow the overlaps.

so we do:

ghci Test.hs

now it does not work (but it did in 6.3), but:

ghci -fallow-overlapping-instances Test.hs

does... Even it Test.hs is the top level module.


Simon Peyton-Jones wrote:

>You have a pragma "-fallow-overlapping-instances" in Test.hs, and indeed
>it is honoured when compiling Test.hs.  But it's not taken into account
>when compiling top-level expressions, or, indeed, if you were to import
>Test into another module.
>If you say ":set -falllow-overlapping-instances" it'll work fine.
>Now, maybe you'd like the flag to attach permanently to the *instance*,
>so that if an instance decl is compiled with
>-fallow-overlapping-instances, then no complaint will ever be issued for
>its overlaps, even if it is imported into a module that doesn't have
>-fallow-overlapping-instances.  That would make sense, I think, but it's
>not implemented and never has been.  
>| -----Original Message-----
>| From: glasgow-haskell-users-bounces at
>| bounces at] On Behalf Of Ralf Lammel
>| Sent: 02 March 2005 08:45
>| To: glasgow-haskell-users at
>| Subject: RE: GHC 6.4 release candidates available
>| I think this is an old bug,
>| or at least I have seen it months back.
>| The "overlapping instances" directive does not make it to the
>| See attached sample with the offending session.
>| Thanks for fixing.
>| Ralf
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