[Haskell-cafe] Trouble installing FileManipCompat

Daniel Fischer daniel.is.fischer at googlemail.com
Wed Jan 5 02:07:17 CET 2011

On Wednesday 05 January 2011 01:54:36, Tony Miller wrote:
> Hi,
> I'm trying to install FileManipCompat(well, really
> HStringTemplateHelpers, but the error is from FileManipCompat) and I'm
> getting this error:
> [1 of 1] Compiling System.FilePath.FindCompat (
> System/FilePath/FindCompat.hs, dist/build/System/FilePath/FindCompat.o
> )
> System/FilePath/FindCompat.hs:175:20:
>     Not in scope: data constructor `State'

Apparently the code is written for an older version of mtl.
As of mtl-2.*, State is no longer a separate type, it's a type synonym for

StateT s Identity


You can try

$ cabal install --constraint="mtl < 2.0" HStringTemplateHelpers

(although having multiple versions of mtl installed may lead to some 
headaches too).

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