> Lisp doesn’t even have "operators" — everything is a function. Gosh, the more you learn about Lisp, the more it feels like we went backwards. Don't learn wro

> Lisp doesn’t even have "operators" — everything is a function. Gosh, the more you learn about Lisp, the more it feels like we went backwards. Don't learn wrong things. Lisp has operators and no, not everything is a function. LET for example is not a function. It is a built-in special operator in Common Lisp. Similar in other Lisp dialects. Scheme R7RS documents "let" as syntax: https://standards.scheme.org/corrected-r7rs/r7rs-Z-H-6.html#TAG:__tex2page_index_158 https://standards.scheme.org/corrected-r7rs/r7rs-Z-H-6.html#... with a "named let" as a variant: https://standards.scheme.org/corrected-r7rs/r7rs-Z-H-6.html#TAG:__tex2page_index_190 https://standards.scheme.org/corrected-r7rs/r7rs-Z-H-6.html#... In Emacs Lisp: https://www.gnu.org/software/emacs/manual/html_node/eintr/let.html https://www.gnu.org/software/emacs/manual/html_node/eintr/le... "The let expression is a special form in Lisp..." Also: limiting the redefinition of standard operators is not backwards, it's useful, to prevent to crash a Lisp, since in Lisp function names are often late bound. -> changing a core function will have immediate effect on all code using that. Macros are also not "function". Macros are operators which expand source code to new source code. Lisp typically has these operator types: * functions, which are operators which get called with evaluated arguments * macros, which are operators, which get called with source code and which return new source code * special operators (QUOTE, LET, DEFUN, SETQ, IF, ...), which are typically hard-wired in the implementation with both syntax and semantics. Scheme has a set of those, too. Additionally one my see fexprs, which are operators, which are called with source code. Then in some Lisps some functions lazy evaluate their arguments. The glossary of Common Lisp explains "operator": https://www.lispworks.com/documentation/HyperSpec/Body/26_glo_o.htm#operator https://www.lispworks.com/documentation/HyperSpec/Body/26_gl... operator n. 1. a function, macro, or special operator. 2. a symbol that names such a function, macro, or special operator. 3. (in a function special form) the cadr of the function special form, which might be either an operator[2] or a lambda expression. 4. (of a compound form) the car of the compound form, which might be either an operator[2] or a lambda expression, and which is never (setf symbol). > You can't redefine it In standard Common Lisp it is UNDEFINED what happens when one redefines a standard operator of Common Lisp. Typical implementations will signal an error (which often provides a restart). Typical implementations will also extend this to other protected packages, such that the user can't accidentally replace an operator and the Lisp system may crash.