A counter in racket-scheme:

#lang typed/racket

(define my-counter!
    (let ([t 0])
        (lambda ()
	        (set! t (+ 1 t))
	    t);lambda
	);let
);define 
(print (my-counter!))
(print (my-counter!))

A counter in sbcl-lisp:

load "~/quicklisp/setup.lisp")

(declaim (optimize (speed 3) (safety 3)))

(let ((c 0))
    (defun my-counter! ()
        (lambda ()
            (setf c (+ 1 c))
	    c); lambda
	 ) ;defun
) ;let

(defun main ()
(print (funcall (my-counter!)))
(print (funcall (my-counter!)))
)

(sb-ext:save-lisp-and-die "test.exe" :toplevel #'main :executable t)

Could someone elaborate why i need “funcall” in lisp and not in scheme ? And why the different placing of let ?

  • Ok_Specific_7749OPB
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    1 year ago

    Why must the variable c be declared outside and before the function definition my-counter!.
    [ If you put it inside the value is always “reset”]

  • funk443B
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    1 year ago

    In Common Lisp, as opposed to Scheme, it is not possible that the car of the compound form to be evaluated is an arbitrary form. If it is not a symbol, it must be a lambda expression, which looks like (lambda lambda-list form*).

    This