[Haskell-cafe] Trouble installing FileManipCompat

[Daniel Fischer]

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

now.

You can try

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

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