How to remove nested parentheses in LISP

Posted by orcik on Stack Overflow See other posts from Stack Overflow or by orcik
Published on 2010-04-21T06:54:08Z Indexed on 2010/04/21 7:13 UTC
Read the original article Hit count: 221

Filed under:

lisp

|

parentheses

How can I remove nested parentheses recursively in Common LISP Such as

  (unnest '(a b c (d e) ((f) g))) => (a b c d e f g)
  (unnest '(a b))                 => (a b)
  (unnest '(() ((((a)))) ()))     => (a)

Thanks

© Stack Overflow or respective owner

Related posts about lisp

Why is Lisp useful?

as seen on Programmers - Search for 'Programmers'
Lisp obviously is an advantage for the AI stuff but it doesn't appear to me that Lisp is any faster than Java, C#, or even C. I am not a master of Lisp, but I find it incredibly difficult to understand the advantage one would get in writing Business Software in Lisp. Yet it is considered as a hacker's… >>> More
Why do you like Lisp ?

as seen on Programmers - Search for 'Programmers'
Why does Paul Graham advocate Lisp? Why did ITA Software choose Lisp over other High Level languages? Lisp obviously is an advantage for the AI stuff but I don't think Lisp is any faster than Java, C# or as a matter of fact faster than C. Still it is considered as a Hackers language? I am not a master… >>> More
Emacs 23.1 make error 139 in Mac OS X 10.6.3

as seen on Stack Overflow - Search for 'Stack Overflow'
When I try to compile GNU Emacs 23.1 on my machine with Mac OS X 10.6.3 I repeatedly get the following ending: Directories: /src/emacs-23.1/lisp/. /src/emacs-23.1/lisp/./calc /src/emacs-23.1/lisp/./calendar /src/emacs-23.1/lisp/./emacs-lisp /src/emacs-23.1/lisp/./emulation /src/emacs-23.1/lisp/./erc… >>> More
Why not port Linux kernel to Common Lisp?

as seen on Stack Overflow - Search for 'Stack Overflow'
Conventional wisdom states that OS kernels must be written in C in order to achieve the necessary levels of performance. This has been the justification for not using more expressive high level languages. However, for a few years now implementations of Common Lisp such as SBCL have proven to be… >>> More
Lisp Style question label local functions or not?

as seen on Stack Overflow - Search for 'Stack Overflow'
I was wondering if there is a standard practice regarding the use of labels in Lisp. I've been messing around with a Lisp implementation of the algorithm described in the first answer here http://stackoverflow.com/questions/352203/generating-permutations-lazily My current version uses labels to… >>> More

Related posts about parentheses

Removing text within parentheses (parentheses within parentheses prob)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am trying to remove text that is within parentheses (along with the parentheses themselves) but am having trouble with the scenario where there are parentheses within parentheses. This is the method I am using (in Ruby): sentence.gsub(/\(.*?\)/, "") and that works fine until I have a sentence… >>> More
remove text in parentheses and the parentheses using .filter() or .slice()

as seen on Stack Overflow - Search for 'Stack Overflow'
i have a table with code like this: <tr> <th scope="row">5-17</th> <td>23.6 (22.0-24.0)</td> <td>18.0 (17-20.0)</td> </tr> <tr> <th scope="row">Total 0-17</th> … >>> More
How to skip parentheses on Netbeans with enter?

as seen on Stack Overflow - Search for 'Stack Overflow'
So I have been programming in C++ with Eclipse and have the habit of hitting enter to skip parentheses (anyone who has ever used eclipse probably knows what I am talking about). I have recently started learning Java and decided to use NetBeans, mostly due to the much more simple interface. However… >>> More
perl parentheses in regular expression

as seen on Stack Overflow - Search for 'Stack Overflow'
I have been trying several regular expressions $str =~ s/^0+(.)/$1/; converts 0000 to 0 and 0001 to 1 $str =~ s/^0+./$1/; converts 0000 to empty string, 000100 to 00, 0001100 to 100. what difference is the parentheses making? >>> More
What do parentheses in a Perl regex do?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have been trying several regular expressions in the substitution operator: $str =~ s/^0+(.)/$1/; converts 0000 to 0 and 0001 to 1 $str =~ s/^0+./$1/; converts 0000 to empty string, 000100 to 00, 0001100 to 100. what difference is the parentheses making? >>> More