On Wed, Jan 29, 2020 at 01:47:12AM +0100, pd wrote: > Hello, > > I'd like to know if there's in picolisp the common lisp concept of places,
Yes, it is called 'var' in the docs, and is either the VAL of a symbol or the CAR of a list cell. > I mean, is it possible to do this: > > (setq L (1 2 3)) > (set (car L) 'x) > L -> (1 x 3) : (setq L (1 2 3)) -> (1 2 3) : (set (cdr L) 'x) -> x : L -> (1 x 3) > (set (cdr L) '(a b)) > L -> (1 a b) : (con L '(a b)) -> (a b) : L -> (1 a b) > I'd say it is not places in picolisp, but reference manual says: > > : (set 'L '(a b c) (cdr L) '999) > -> 999 > : L > -> (a 999 c) > > Which seems similar to places or at least to the use of setf in common > lisp, but what I find strange is in my understanding the set form above > should lead to L -> (a 999) or even (a . 999) because (cdr L) is (b c) and > thus replacing cdr L with 999 leads to (a 999)... where's my error? (cdr L) returns the second CELL in the list. 'set' sets the CAR of that cell. > Also, if not having places, have we got scheme's setcar and setcdr at least? I don't know Scheme, but setcar should be 'set' and setcdr is 'con'. > Is there any way of manipulating parts of lists and even objects rather > than using specific functions such as delete, replace and so on ? Yes, sure, that's all what Lisp is about :) ☺/ A!ex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
