Document SpockM, SpockCtxM, WebStateM, WebStateT, ActionT, ActionCtxT

[Profpatsch]

All of these types have no docstrings, and it’s not obvious what part of the stack they represent. Thus as a user one has to infer it by clicking through type aliases (practically every time, since the naming scheme is not at all obvious and hard to remember).

[agrafix]

Would you like to help with this via PR?

[Profpatsch]

I can try, of course you’d have to annotate.