> why is the syntax defined this way? Because Lisp has two syntax levels: one of s-expressions and one for the programming language on top of s-expressions. S

> why is the syntax defined this way? Because Lisp has two syntax levels: one of s-expressions and one for the programming language on top of s-expressions. S-expression examples (berlin madrid london) (john (age 21) (weight 65)) Lisp code examples: (if (> a b) a b) Non Lisp code, but a valid S-expression: (if (> a b) then a else b) You can define a new syntax for Lisp - like it has been done before - where you traditional syntax to define a programming language. You then just need a grammar and a parser. Originally s-expressions were only thought for data and programs would have a different syntax. A conditional might be written like that. cond a > b -> a ; t -> b Lisp code with lists might then look like: append[ (a,b,c) , car[list] ] Where (a,b,c) is a literal list of three symbols. But the Lisp system was internally defined using lists and the compiler&interpreter were using Lisp code as lists. Thus it was seemed more practical to just work with s-expressions (nested lists, ...) and defer the question of syntax to a later time. Later multiple attempts had been made to define a Lisp with a more traditional syntax: the Lisp 2 effort in the 60s, various syntactic front ends, RLISP, LOGO, ML, Dylan, ... . But for Lisp programmers it was more practical to keep the s-expression syntax, because the internal machineries of Lisp are using s-expressions anyway