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From: "Pascal J. Bourguignon" <p...@informatimago.com>
Newsgroups: comp.lang.lisp
Subject: Re: LISP style question - (with-open-file)
Date: Tue, 29 May 2012 18:20:05 +0200
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ccc31807 <carte...@gmail.com> writes:

> On May 29, 11:46 am, Norbert_Paul <norbertpauls_spam...@yahoo.com>
> wrote:
>> What you have writte is no recursion but a statically (lexically)
>> nested expression, but you are right: It is possible to make recursive
>> function calls in Lisp.
>
> Which actually responds to a question I didn't ask.
>
> With Perl, you can manipulate a file line by line, which would process
> a file that contains one record per line in a row oriented framework
> (like a line in a spreadsheet or a row in a database table. Or, you
> can use slurp mode to manipulate the entire file as one long string,
> if (for example) you wanted to manipulate a text file.
>
> In order to recurse on a CSV file, you would need to read the entire
> file into memory as a list, with each record becoming a list element.

There are several libraries to read or write CSV files.

(ql-dist:system-apropos "csv")


> (defun munge-data (file)
>   (cond
>     ((null file) nil)
>     (t (manipulate-record (car file))
>        (munge-data (cdr file)))))
>
> To me, it's more intuitive, less space intensive, and maybe less time
> intensive, to manipulate a file line by line iteratively that
> recursively.
>
> Comments?

Indeed.  But how often do you have to process files bigger than the RAM
nowadays?  (eg. I have 24GB of RAM in my workstation, and 4GB in my game
computer).

But yes, if you have to process multi-terabyte log files, better do it
in chunks.

clhs read-line


-- 
__Pascal Bourguignon__                     http://www.informatimago.com/
A bad day in () is better than a good day in {}.