As a Clojurist the standard pattern for ensuring keys-are-set before doing-something is not-as-elegant-as-this. Clojure is full of macros that do useful things :) Simplifying oft-used patterns into compact representations is very on-brand. Plus, you need this like, all the time.

This will eliminate two whole classes of errors: 1) where keys are supplied a value at an undesired nesting-level. 2) where keys are not-yet-set for some other reason.

For the many programmers who have to write in checks and verifications themselves for this, this saves quite a bit of time, removing the interruption from coding and restoring the flow of getting logic-to-symbol.