The built-in definition of a Clojure function allows the compiler to view the operator as a macro, not as a function. The problem is that you have to provide a separate macro body that should have nothing to do with the function body. You can define the embedded version + that actually did - !
This is very doubtful and completely undocumented. It seems to be used to install faster code for small core functions.
In contrast, in C ++, inline is a hint for the compiler to consider the built-in extension of any function call. Expanding a string requires the same semantics as a regular function call. Functions of accessories and mutators are often built-in.
It is odd to find an aspect of the Clojure language with soggier semantics than the corresponding C ++.
I thought the function was deprecated. Is not. This is a similar definline operator, which is not obsolete, but experimental. To be obsolete, it would have to be created in the first place, and it never reached this stage.
I am grateful to Alan Malo for the corrections above.