Cannot update cabal (Windows PATH issue)

[r0ml]

On Windows with Haskell Platform 2010.1.0.0 :

• The all-users PATH variable contains %INSTALLDIR%\lib\extralibs\bin.
• The user-specific PATH variable contains %APPDATA%\cabal\bin.

This causes a problem because :

• Every directory in the all-users PATH variable is always checked first, so the shell always uses %INSTALLDIR%\lib\extralibs\bin\cabal.exe.
• cabal install cabal-install only updates %APPDATA%\cabal\bin\cabal.exe rather than both.
• So, you effectively can't update cabal on Windows.

Workaround: Delete %INSTALLDIR%\lib\extralibs\bin\cabal.exe.

[r0ml]

I'm not really sure what is the right way to fix this. Adding ~/cabal/bin to all-users PATH is wrong, and adding %INSTALLDIR%/bin only to the current user's PATH will break things for other users. Perhaps we should recommend doing cabal install --global when replacing executables that come with the platform?