[Haskell-cafe] Cabal Compiler Flag Problem

Ivan Miljenovic ivan.miljenovic at gmail.com
Wed Mar 24 01:30:30 EDT 2010

On 24 March 2010 16:26, Ben Derrett <ben.derrett at googlemail.com> wrote:
> cabal install cgi
> Resolving dependencies...
> Configuring MonadCatchIO-mtl-
> Preprocessing library MonadCatchIO-mtl-
> Building MonadCatchIO-mtl-
> [1 of 1] Compiling Control.Monad.CatchIO ( Control/Monad/CatchIO.hs,
> dist/build/Control/Monad/CatchIO.o )
> Control/Monad/CatchIO.hs:146:34:
>     Illegal signature in pattern: E.SomeException

Interesting.... the code is obviously using extensible-exceptions but
it doesn't seem to work.  What version of GHC are you using?

>         Use -XPatternSignatures to permit it
> cabal: Error: some packages failed to install:
> MonadCatchIO-mtl- failed during the building phase. The exception
> was:
> exit: ExitFailure 1
> cgi-3001.1.8 depends on MonadCatchIO-mtl- which failed to install.
> So, I modified my /root/.cabal/config with:
> -- flags: -XPatternSignatures

Nah, that's a GHC flag not a Cabal/cabal-install flag, so you'd have
to edit the .cabal file to add that in (where it says ghc-options).

Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com

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