[Haskell-cafe] Cabal dependencies
jose.lopes at ist.utl.pt
Sat Oct 6 22:40:15 CEST 2012
OK. Got it!
Do you have any suggestions to install xmobar in this particular case?
On 06-10-2012 19:08, Yuras Shumovich wrote:
> On Sat, 2012-10-06 at 18:25 +0200, José Lopes wrote:
>> But, wouldn't it be possible for xmobar to use mtl-22.214.171.124 and for
>> parsec to use mtl-2.1.1, while xmobar would use this parsec version?
>> In this case, I am assuming that mtl-126.96.36.199 and mtl-2.1.1 are
>> considered two different libraries.
> Usually it leads to "strange" compilation errors.
> Package A:
> data AA = AA String
> func0 :: Int -> AA
> func0 n = AA $ replicate n "A"
> func1 :: AA -> Int
> func1 (AA str) = length str
> Package B:
> import A
> func2 :: AA -> Int
> func2 aa = func1 + 1
> Package C:
> import A
> import B
> func3 :: Int -> Int
> func3 n = func2 $ func0 n
> If C and B are compiled with different versions of C,
> then func3 will not compile. Compiler will say that
> AA returned by func0 doesn't match AA expected by func2
> More real examples:
José António Branquinho de Oliveira Lopes
Instituto Superior Técnico
Technical University of Lisbon
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