-ddump-minimal-imports breaks qualified imports (import...as)

[guest]

When using the -ddump-minimal-imports option on a Haskell file, it breaks qualified imports.

Ie, suppose one has a line in a file thus:

 import qualified Data.ByteString as B (putStr, readFile)

Using -ddump-minimal-imports will give you something like this:

 import Data.ByteString(B.putStr, B.readFile)

There are 3 things wrong here:

• putStr and readFile should not be renamed thus, as obviously Data.ByteString has nothing under those names

• Data.ByteString is no longer being imported under a different name, so all function uses relying on B.putStr etc. will break

• Finally, it's just ugly to have no spaces between the last letter of the module's name and the opening parenthesis.

I see this behavior under GHC 6.6.1, and asl of #haskell tells me he duplicated the import problem using GHCi version 6.8.0.20071019.

-- gwern

[guest]

Example program:

module Main where

import System
import qualified Data.ByteString as B

f .>> g = \x -> f x >>= g

main = getArgs >>=
          ((sequence .) $ map (B.readFile .>> B.putStr))

-ddump-minimal-imports produces:

import System(getArgs)
import Data.ByteString(B.putStr, B.readFile)

which should read:

import System(getArgs)
import qualified Data.ByteString as B(B.putStr, B.readFile)

[simonpj]

Good point. This is one of those fiddly things, and few people use it. So I'm going to put it as low priority, currently provisionally in the 6.10 queue.

Others: pls yell and add yourselves to the cc list if you use -ddump-minimal-imports.

Simon

[igloo]

Fixed by:

Mon Jul  6 12:25:03 BST 2009  simonpj@microsoft.com
  * Major patch to fix reporting of unused imports