[Haskell-cafe] How efficient is read?

[Gwern Branwen]

On Mon, May 10, 2010 at 4:50 PM, Tom Hawkins <tomahawkins at gmail.com> wrote:
>> In fact, if you just want
>> Read-like functionality for a set of Haskell datatypes, use polyparse: the
>> DrIFT tool can derive polyparse's Text.Parse class (the equivalent of Read)
>> for you, so you do not even need to write the parser yourself!
>
> Cabal install DrIFT-cabalized complains.  What is the module "Rules"?
> I've never seen it before.
>
> Is there a quick fix?  I didn't see a "build-depends" line in my
> ~/.cabal/config file.
>
>
>
> e0082888 at e0082888-laptop:~$ cabal install DrIFT-cabalized
> Resolving dependencies...
> Configuring DrIFT-cabalized-2.2.3.1...
> Preprocessing executables for DrIFT-cabalized-2.2.3.1...
> Building DrIFT-cabalized-2.2.3.1...
>
> src/DrIFT.hs:19:17:
>    Could not find module `Rules':
>      It is a member of the hidden package `ghc-6.12.2'.
>      Perhaps you need to add `ghc' to the build-depends in your .cabal file.
>      Use -v to see a list of the files searched for.
> cabal: Error: some packages failed to install:
> DrIFT-cabalized-2.2.3.1 failed during the building phase. The exception was:
> ExitFailure 1

The tarball was missing its Rules.hs; as it happens, GHC has a module
named Rules.hs as well, hence the confusing error. I've uploaded a
fresh one that should work.

-- 
gwern