wasp: Improve error handling in Generator - come up with monad transformer stack for Generator

Great, thanks @Martinsos for your quick take! This is super helpful and will unblock me to hopefully to get closer towards a Draft PR today (and hopefully ready for review tomorrow). I really appreciate the thoughts! 👍🏻 🚀

@shayneczyzewski thanks for this, this is very cool!

Regarding additional level of interface, so we don’t deal directly with ask but instead we have functions on top of it -> yes, I like that very much, was considering proposing that at some point actually. I love looking at a monad like this as a type and bunch of functions on it, and while ask is a function on it, it is a bit too close to the implementation. So I think this is a no-brainer and great approach.

As for Has... approach -> makes sense! I think you explained pros/cons in great way. The only thing I fear is that we introduce more complexity than we take away, which is not easy to judge at the moment. But it is certainly attractive, and the idea of specifying granular dependencies on type level is really attractive. This does though mean we have to define a type class for each of those. But that might be ok. Interesting interesting!

Hm it seems we are slowly coming up with a gradual plan to attack this problem. It is obviously not yet completely clear, but it is shaping well for sure! Thanks for the effort, looking forward to see what you suggest next!

Did some simple experimenting locally and made it runnable here just in case anyone wants to get a feel for it all: https://replit.com/@smcnc/ReaderT-ExceptT-playground#Main.hs

Note: You can just check out the Main.hs file if you want. It won’t Run out of the box (replit quirk it seems), but if you fork and follow README directions you can get it running pretty easily.

Hey @Martinsos thanks for the example. I think planning ahead if we think we will need it, which it does sound like here, makes sense. I’m good with creating a Generator monad that is first just ExceptT! 👍🏻 Will start on it, thanks.

Think about how to handle warnings, so we may be able to do other things like show “Need to migrate” in browser when running wasp start and Prisma schema changed. This could be handled with different error severity levels.