An inline function is a function which gets textually inserted by the compiler, much like a macro.
Like macros, performance is improved by avoiding the overhead of the call itself, and (especially!) by the compiler being able to optimize through the call (
procedural integration'). Unlike macros, arguments to inline fns are always evaluated exactly once, so thecall’ is semantically like a regular function call only faster. Also unlike macros, argument types are checked and necessary conversions are performed correctly.