Thanks!
On 06-10-2012 23:07, Yuras Shumovich wrote:
On Sat, 2012-10-06 at 22:40 +0200, José Lopes wrote:
OK. Got it!
Do you have any suggestions to install xmobar in this particular case?
In case of executables I usually rm -rf ~/.ghc, cabal install,
and rm -rf ~/.ghc again. Executables are still here (in ~/.cabal/bin),
but all libraries are lost. Warning: it may break your development
environment, so make sure you know what you are doing.
Better solution could be sandbox tools like cabal-dev. They alloy you to
setup development environment per project.
Thanks,
José
On 06-10-2012 19:08, Yuras Shumovich wrote:
On Sat, 2012-10-06 at 18:25 +0200, José Lopes wrote:
OK.
But, wouldn't it be possible for xmobar to use mtl-2.0.1.0 and for
parsec to use mtl-2.1.1, while xmobar would use this parsec version?
In this case, I am assuming that mtl-2.0.1.0 and mtl-2.1.1 are
considered two different libraries.
Usually it leads to "strange" compilation errors.
E.g.
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:
http://stackoverflow.com/questions/11068272/acid-state-monadstate-instance-for-update
http://stackoverflow.com/questions/12576817/couldnt-match-expected-type-with-actual-type-error-when-using-codec-bmp/12577025#12577025
Thanks,
José
--
José António Branquinho de Oliveira Lopes
Instituto Superior Técnico
Technical University of Lisbon
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