I try this LISP snippet from the Structure and Interpretation book
(define (a-plus-abs-b a b)
((if (> b 0) + -) a b))
in emacs by C-x C-e, or by evaluating the whole buffer. either way and get the backtrace:
Debugger entered--Lisp error: (void-function define)
(define (a-plus-abs-b a b) ((if (> b 0) + -) a b))
(progn (define (a-plus-abs-b a b) ((if (> b 0) + -) a b)))
eval((progn (define (a-plus-abs-b a b) ((if (> b 0) + -) a b))) t)
elisp--eval-last-sexp(nil)
eval-last-sexp(nil)
funcall-interactively(eval-last-sexp nil)
call-interactively(eval-last-sexp nil nil)
command-execute(eval-last-sexp)
If I try {evaluate-defun} I get a different error: symbol's definition is void: define
what is the proper way to evaluate the snippet? should I be using sth outside emacs?
Either way of executing Emacs Lisp works.
What the issue here is that SICP uses a Lisp called Scheme. This is a language that differs from Emacs Lisp. The main difference is that Scheme is a Lisp-1 and so a variable and a function can't have the same name and so define is used to create both. Whilst Emacs Lisp is a Lisp-2 and you can have a function and a variable with the same name, so defun to define a function and defvar for a variable - or usually setq to set a variables value and also define it if required.
If you want to try SICP you need to get a Scheme interpreter or possibly Racket and use its Scheme language mode.