Harendra Kumar harendra.kumar at
Sat Aug 20 04:50:17 UTC 2016

Thanks Albert! That clarifies the behavior. We had discussion on this in as well where ezyang
provided clarifications on the behavior. We need to update the
documentation to make it more precise and accurate. I will file a ticket
for that.


On 20 August 2016 at 06:37, Albert Y. C. Lai <trebla at> wrote:

> On 2016-08-16 07:08 AM, Harendra Kumar wrote:
>> As per the GHC manual
>> (
>> ges.html#the-ghc-package-path-environment-variable
>> <
>> ges.html#the-ghc-package-path-environment-variable>),
>> packages which come earlier in the GHC_PACKAGE_PATH supersede the ones
>> which come later. But that does not seem to be the case always.
>> I am dealing with a case where I have multiple versions of a package in
>> different databases.
> No, they don't mean multiple versions. They mean this:
> For example if two databases both have HUnit-1.1 (important: same name and
> same version number), then that's when all the talk about overriding is
> relevant.
> If you have different version numbers, the override rule doesn't apply,
> the rule that applies is the shadow rule: the highest version number wins.
> The shadow rule exists because there are two scenerios that you really
> don't want to behave differently:
> 1. You have both HUnit-1.1 and HUnit-1.2, and they are in the same
> database.
> 2. You have both HUnit-1.1 and HUnit-1.2, but they are in different
> databases.
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