[Haskell-beginners] two System.IO.Strict modules

[Patrick Wheeler]

It is also possible to refer to a package explicitly durring import with
the PackageImports language pragma.  You can read about it in the ghc
manual[1].

Patrick

[1]
http://www.haskell.org/ghc/docs/7.2.1/html/users_guide/syntax-extns.html#package-imports

On Fri, Apr 26, 2013 at 10:10 PM, Hong Yang <hyangfji at gmail.com> wrote:

> Thanks.
>
>
> On Fri, Apr 26, 2013 at 8:33 AM, Brandon Allbery <allbery.b at gmail.com>wrote:
>
>> On Thu, Apr 25, 2013 at 11:12 PM, Hong Yang <hyangfji at gmail.com> wrote:
>>
>>> There are two modules called the same name: System.IO.Strict, documented
>>> respectively at
>>>
>>> http://hackage.haskell.org/packages/archive/strict-io/0.2.1/doc/html/System-IO-Strict.html
>>>     http://hackage.haskell.org/package/strict-0.3.2
>>>
>>> My questions are:
>>>
>>> 1)    Will these two modules coexist in the same version of GHC? Or put
>>> it another way, both modules' .tar.gz files have System/IO/Strict.hs
>>> inside, will they overlap in physical disk? From where can I tell which
>>> locations they will be installed to?
>>>
>>
>> Each module gets its own directory tree under /usr/lib/ghc or ~/.ghc.
>>
>>
>>> 2)    If yes, which module will "import System.IO.Strict" actually use?
>>>
>>
>> This is a bit harder; it will try to pick one, but I don't know the
>> rules. Ultimately it's best to use -package parameters to tell it which
>> package to take it from.
>>
>> This is where building with cabal-install helps, as you specify the
>> package to use in the manifest and only the packages listed in the manifest
>> will be visible to ghc.
>>
>> --
>> brandon s allbery kf8nh                               sine nomine
>> associates
>> allbery.b at gmail.com
>> ballbery at sinenomine.net
>> unix, openafs, kerberos, infrastructure, xmonad
>> http://sinenomine.net
>>
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>
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-- 
Patrick Wheeler
Patrick.John.Wheeler at gmail.com
Patrick.J.Wheeler at rice.edu
Patrick.Wheeler at colorado.edu
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