Difficulty creating a ConnectionManager instance

[imalsogreg]

With new type for withConn :: (conn -> m a) -> conn -> m a, I'm confused about how to write a ConnectionManager instance for snap that defers to the ConnectionManager instance for Pool Postgresql.

What I have so far:

data App = App { _heist :: Snaplet (Heist App), _db :: Pool Postgresql }

instance ConnectionManager App where
  withConn f app@(App _ pg) = do
    pgConn <- extractConnection return pg
    let g = _ f
    withConn g pgConn

It seems I need to somehow create a function g :: Postgresql -> m a out of the function f :: App -> m a if I want to use Postgresql's ConnectionManager instance, but it seems impossible to generate such a function.

Maybe I'm going down the wrong route? The ultimate goal is just to provide a convenience function for running groundhog queries from within my Handler App App monad.

[lykahb]

Hi @imalsogreg. Sorry, I was not able to put as much effort to Groundhog as before and seldom checked the notifications. Have you found a solution for this issue?

[imalsogreg]

No problem @lykahb :) Thanks for checking!

I have at least a workaround for now. Rather than write a instance ConnectionManager App, I just use the instance from the connection itself. Do you think you will step back from groundhog permanently? If so, would you like help maintaining it?

[lykahb]

I plan to support Groundhog indefinitely and release pipes/conduit integration sometime in the future. Yet, it would be hard to keep the same level of activity as a couple of years ago. Any help with the maintenance would be invaluable.