> And some Scheme code: (if (cond) (begin (preamble) (define a 5) (do-stuff a)) (do-stuff 6)) This is not defi

> And some Scheme code: (if (cond) (begin (preamble) (define a 5) (do-stuff a)) (do-stuff 6)) This is not defining a local variable in Scheme. The various Scheme standards also require that DEFINE appears at the top of a body. > Common Lisp wants you to declare every set of intermediate variables in a nested scope Lisp programmers edit code by list operations. For example, I can set the cursor between (preamble) and the (let ...) form. control-meta-t transposes the lists. The let form is moved upwards and the enclosed body is moved, too. Try that in the C code. Code transformations are vastly easier with explicit scopes. JavaScript has introduced a LET for a reason: block scope is clearer than VAR (function / global scope). (defun foo (a) (if a (var b a)) (print b)) ; what's the value here? In Common Lisp above would not be valid. I would need to write: (defun foo (a) (let (b) (if a (setf b a)) (print b))) I can then immediately see that each B is inside a LET scope, which defines it. It's just by simply moving upwards in the expression tree. I would not need to search the whole expression tree. Also languages may do different things with definitions inside conditional expressions.