[ajmoon]

I agree it feels a bit counter to the philosophy of Clojure. It's adding new syntax to the language for map destructuring only (that will need to be implemented in cljs and other runtimes for consistency) and it's a purely runtime check as we don't know the map's keys at compile time. I don't see what new kind of safety it adds that's not achievable with existing solutions such as :pre or doing an assert inline.

I feel there are better solutions to this problem that already exist, such as using spec/malli and validating the value properly rather than just checking for presence.

[fogus]

One philosophy of Clojure is to facilitate building practical and robust systems. In practice, people do runtime checking of maps using punning, some kind of `nil` check, or a more ponderous `(get m k sentinel)` checking pattern. The new feature obviates the latter as destructuring syntax in the vast majority of cases where the absence of the key throws. It's opt-in, so if Malli/Spec work then you don't need to use this. I will say that we have some other things brewing that compose well with `:keys!` and friends and the 1.13 release is going to DRY a lot of existing and future Clojure code.