[Haskell-cafe] How to determine correct dependency versions for a library?

[Vincent Hanquez]

On 11/14/2012 09:53 AM, Ivan Lazar Miljenovic wrote:
>    % cabal install virthualenv
>    Resolving dependencies...
>    cabal: Could not resolve dependencies:
>    trying: virthualenv-0.2.1
>    rejecting: base-3.0.3.2, 3.0.3.1 (global constraint requires installed
>    instance)
>    rejecting: base-4.6.0.0/installed-eac... (conflict: virthualenv =>
>    base>=4.2.0.0 && <4.6)
>    rejecting: base-4.6.0.0, 4.5.1.0, 4.5.0.0, 4.4.1.0, 4.4.0.0, 4.3.1.0, 4.3.0.0,
>    4.2.0.2, 4.2.0.1, 4.2.0.0, 4.1.0.0, 4.0.0.0 (global constraint requires
>    installed instance)
> Doesn't this prevent the error of "this package won't build" (even if
> the error message doesn't precisely say that)?
In most cases, it replaces the uncertainty of a build error with an 
unconditional pre-build error.

instead of having either a package built or a meaningful build error, i 
now have no package with the information that it might or might not 
cause an error to continue.

-- 
Vincent