[Haskell-cafe] What am I missing? Cycle in type synonym declarations

This file gives me the error "Cycle in type synonym declarations" Can anyone tell me why? I'm just trying to write a function to create a type that is a FooT with the type parameter fixed. {-# LANGUAGE TemplateHaskell #-} import Language.Haskell.TH (Q, Dec, TypeQ) data FooT a = FooT a foo :: TypeQ -> Q [Dec] foo t = [d| type Bar = FooT $t |]