&gt; If you have actual numerical calculations that are compile-once, run-many-many-many-times, then you will see a huge performance benefit<p>I agree, and I haven&#x27;t found anything like this in other (non-exotic) languages.  I recently wrote a function using the @generated macro to produce Wigner-D matrices via the recursion relations.  The function dispatches on the size of the matrix (using Type{Val{N}}) and after it compiles once for a particular value of N, all future calls are blazing fast (since the machine code is essentially just a long list of multiply and add instructions).