On thing to keep in mind when you see the language, which evolved of several decades: it has low-level (go to, ...), mid-level (macros, ...) and high-level (CLO

On thing to keep in mind when you see the language, which evolved of several decades: it has low-level (go to, ...), mid-level (macros, ...) and high-level (CLOS + MOP) elements in one language. A reason for that: the low-level parts are code generation building blocks for the higher level parts. Example: The SERIES library (a higher-level way to think about loops and sequences) uses macros (mid-level) to transform code into efficient loops (-> low-level): https://github.com/rtoy/cl-series https://github.com/rtoy/cl-series So one reason for all this functionality is: the language is its own compilation target. One is not supposed to write all the code, but we can write code which writes the lower-level code.