Not sure if this is a bug that I should file on Trac or if this is just a newbie mistake... Here's the error during cabal install:

Resolving dependencies...
Configuring FieldTrip-0.2.7...
Preprocessing library FieldTrip-0.2.7...
Building FieldTrip-0.2.7...
[ 1 of 17] Compiling Graphics.FieldTrip.ParamSurf ( src/Graphics/FieldTrip/ParamSurf.hs, dist/build/Graphics/FieldTrip/ParamSurf.o )
[ 2 of 17] Compiling Graphics.FieldTrip.Transform ( src/Graphics/FieldTrip/Transform.hs, dist/build/Graphics/FieldTrip/Transform.o )
[ 3 of 17] Compiling Graphics.FieldTrip.Vector2 ( src/Graphics/FieldTrip/Vector2.hs, dist/build/Graphics/FieldTrip/Vector2.o )

src/Graphics/FieldTrip/Vector2.hs:29:48:
    Module
    `Graphics.Rendering.OpenGL.GL.CoordTrans'
    does not export
    `Vector2(..)'
cabal: Error: some packages failed to install:
FieldTrip-0.2.7 failed during the building phase. The exception was:
ExitFailure 1

I have all the dependencies installed, so I don't think that's the problem...