deleting a nth element of a list

[Arseny Slobodjuck]

Which is the best way to delete some element, whose number is known
from a list ? Is it the following ?

(delete-if (lambda (x) t) some-list :start i :count 1)

thanks

[Erik Naggum]

* Arseny Slobodjuck

| Which is the best way to delete some element, whose number is known
| from a list? Is it the following?

Clever solution, but I tend to think that plain old ordinary list
hacking is simpler:

(defun delete-nth (n list)
(if (zerop n)
(cdr list)
(let ((cons (nthcdr (1- n) list)))
(if cons
(setf (cdr cons) (cddr cons))
cons))))

#:Erik
--
If this is not what you expected, please alter your expectations.

[Francis Leboutte]

Erik Naggum <er...@naggum.no> wrote:

>* Arseny Slobodjuck
>| Which is the best way to delete some element, whose number is known
>| from a list? Is it the following?
>
> Clever solution, but I tend to think that plain old ordinary list
> hacking is simpler:
>
>(defun delete-nth (n list)
> (if (zerop n)
> (cdr list)
> (let ((cons (nthcdr (1- n) list)))
> (if cons
> (setf (cdr cons) (cddr cons))
> cons))))

Would prefer this :
(defun delete-position (n list)

(if (zerop n)
(cdr list)
(let ((cons (nthcdr (1- n) list)))

(when cons
(setf (cdr cons) (cddr cons)))
list)))

>#:Erik

--
Francis Leboutte
f...@algo.be www.algo.be +32-(0)4.388.39.19

[Markus B. Krüger]

Erik Naggum <er...@naggum.no> writes:

> * Arseny Slobodjuck
> | Which is the best way to delete some element, whose number is known
> | from a list? Is it the following?
>
> Clever solution, but I tend to think that plain old ordinary list
> hacking is simpler:

However, the delete-if solution would work for any sequence, not just
lists.

--
'------------------- Markus Bjartveit Krüger ---------------------`
' `
` E-mail: mar...@pvv.org WWW: http://www.pvv.org/~markusk/ '
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