Try using an older GHC on AppVeyor.
Try using an older GHC on AppVeyor.

diku-dk/futhark,diku-dk/futhark,HIPERFIT/futhark,diku-dk/futhark,HIPERFIT/futhark,HIPERFIT/futhark,diku-dk/futhark,diku-dk/futhark