Aliasing current module qualifier

[Andreas Abel]

Indeed, being able to introduce a short name for the current module, or 
having a fixed short name like 'This' or 'Self' would be neat.

The standard workaround for your example would be

   import Prelude hiding (length,null)

Did you try a .hs-boot file with your self-import trick?

Cheers,
Andreas

On 29.09.2014 10:19, Herbert Valerio Riedel wrote:
> Hello *,
>
> Here's a situation I've encountered recently, which mades me wish to be
> able to define a local alias (in order to avoid CPP use). Consider the
> following stupid module:
>
>
>      module AnnoyinglyLongModuleName
>         ( AnnoyinglyLongModuleName.length
>         , AnnoyinglyLongModuleName.null
>         ) where
>
>      length :: a -> Int
>      length _ = 0
>
>      null :: a -> Bool
>      null = (== 0) . AnnoyinglyLongModuleName.length
>
>
> Now it'd be great if I could do the following instead:
>
>      module AnnoyinglyLongModuleName (M.length, M.null) where
>
>      import AnnoyinglyLongModuleName as M -- <- does not work
>
>      length :: a -> Int
>      length _ = 0
>
>      null :: a -> Bool
>      null = (== 0) . M.length
>
> However, if I try to compile this, GHC complains about
>
>      AnnoyinglyLongModuleName.hs:4:1:
>         Bad interface file: AnnoyinglyLongModuleName.hi
>             AnnoyinglyLongModuleName.hi: openBinaryFile: does not exist (No such file or directory)
>
> while GHCi tells me:
>
>      Module imports form a cycle:
>        module ‘AnnoyinglyLongModuleName’ (AnnoyinglyLongModuleName.hs) imports itself
>
>
> Is there some other way (without CPP) to create a local alias for the
> current module-name? If not, is there a reason GHC couldn't support this
> special case of self-aliasing the current module name?
>
>
> PS: Alternatively, this could be done as a language extension but that'd
>      require extending the Haskell grammar:
>
>      module AnnoyinglyLongModuleName as M (M.length, M.null) where
>
>
> Cheers,
>     hvr
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-- 
Andreas Abel  <><      Du bist der geliebte Mensch.

Department of Computer Science and Engineering
Chalmers and Gothenburg University, Sweden

andreas.abel at gu.se
http://www2.tcs.ifi.lmu.de/~abel/