Hello Frédéric, On Thu, Dec 13, 2018 at 09:15:41AM +0000, PICCA Frederic-Emmanuel wrote:
Hello,
I try to write this sort of code
[...] . but when I try to compile this I get this error. How can I teach ghc how to solve this issue ?
This
src/XdsMe.hs:211:22-43: error: • Could not deduce (MonadThrow Action) arising from a use of ‘toRuchePath’
Must has to mean that *inside* the do block starting with toFilePath uploaded %> \_out -> do `MonadThrow` does not work. I stress inside vs. outside because the outermost `do` block is of type `ReaderT Beamline IO ()` (which *is* an instance of `MonadThrow`), while `Action` apparently is not. I can think of two solutions: - Make `Action` an instance of `MonadThrow` - Let the throw happen outside that `do` block Let us know if that helped -F