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

[Brandon Allbery]

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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