On Mon May 22 09:45:49 UTC 2017, Saurabh Nanda wrote:

Is there any way to have as single TH function, define a type, and use the type, as well?

In short, no. You must define/compile the TH function in a separate module, then import to where you want to use it. See second bullet of this: https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts... And any intro to TH will also explain why it's hard. At first I was puzzled why you didn't get an error message explaining that more clearly, but I can see your usage of the TH function is also incorrect. You're trying to make a data declaration. So that must appear at top level in the program. It makes no sense to appear inside a monad. Also I suspect the imported TH function `makeAdaptorAndInstance` is trying to generate an instance declaration. This must also appear at top level, not inside a monad.

Cross-posted from StackOverflow: ...

Yes, that answer has also moved the $( ... ) to top level. AntC