It's theoretically possible to discern the schemas from the
fdef (if one exists) rather than have the user supply schema.
For example, instead of
(attach-query ::input ::output handler) you could just do
(attach-query handler) and the function would find an
fdef associated with
handler, detect the
:ret (thanks @devurandom) and use these in place of input and output specs.
This is just sugar, really, but might help with onboarding