Please don't deprecate Haskell 98 modules.

Bas van Dijk v.dijk.bas at
Mon Mar 15 16:47:43 EDT 2010

On Mon, Mar 15, 2010 at 3:19 AM, Isaac Dupree
<ml at> wrote:
> On 03/14/10 22:11, Brandon S. Allbery KF8NH wrote:
>> On Mar 14, 2010, at 17:55 , Gwern Branwen wrote:
>>> On Sat, Mar 13, 2010 at 11:06 AM, Ian Lynagh <igloo at> wrote:
>>>> On Fri, Mar 12, 2010 at 08:44:46PM -0500, Gwern Branwen wrote:
>>>>> multiple patches which consisted solely of one line removing haskell98
>>>>> from the .cabal because the haskell98 modules *were not imported*.
>>>> A general "Nothing from dependency is imported" warning would be great,
>>>> but trickier to implement. It's a similar problem to implementing
>>>> an "extension isn't used" warning.
>>> I've opened a ticket for this:
>> Actually, doesn't the instances-are-global thing make this essentially
>> impossible without whole-program analysis?
> GHC will not find an instance that's never imported, I believe. Therefore
> dependencies that are nowhere imported can always be safely removed.  Is
> this right?

No, there are packages that instead of exporting modules, export C
header files like bindings-DSL for example:

Removing such a dependency will break your build if you #include these
header files.

However, maybe bindings-DSL is the only example of this type of package.



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