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Topics - ghfischer

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#1
newLISP newS / A custom push-assoc
May 03, 2008, 01:02:31 PM
During the assoc discussion I came across a problem I'm sure I knew how to solve a year or two ago, but I can't figure out anymore.



I know I'll only have assoc lists of the form
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((a (1 2)) (b (3 4)) ...)

I want to write a function like
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(push-assoc key value assoc-lst)

The only way I could get it to work is if I instead had a global assoc-lst that I used.
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(set 'alst '())
(define (push-assoc k v )
  (if (lookup k alst)
    (assoc-set (alst k) (list k (append (last $0) (list v))))
    (push (list k (list v)) alst -1)))


Any suggestions on how to make this so I can pass in the assoc-lst ?

I tried using a define-macro but failed.

I think I'm just missing something obvious.
#2
newLISP newS / Corner case date issue in daylight savings time.
March 30, 2008, 10:11:14 AM
I'm working on adding some date syntactic sugar for newlisp.  Inspired by the ease of use of certain date manipulation in Ruby.



During my tests I noticed what i think is an issue in some of the date routines related to offset or possibly daylight savings time.  I tried to implement a newlisp version of http://snippets.dzone.com/posts/show/2099">days_in_month.



(Note: I'm in Austin, TX CDT which means my GMT offset is -0500 ==> 300 offset)



(Also note that if I use (date-value) without any options I don't need to specify an offset to get the correct datetime)


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newLISP v.9.3.5 on OSX IPv4 UTF-8, execute 'newlisp -h' for more info.

> (date (date-value 2008 1 1) 300 "%Y %m %d")
"2007 12 31"
> (date (date-value) 0 "%Y %m %d"))
"2008 03 30"


Playing around a bit I found this


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> (date (date-value) 300 "%z")
"-0500"
> (date (date-value 2008 3 1 0 0 0) 300 "%d")
"29"
> (date (date-value 2008 3 1 0 0 1) 300 "%d")
"29"
> (date (date-value 2008 3 1 1 0 0 ) 300 "%d")
"01"


It looks like there's some issue that can be solved by adding an hour.

Upon further investigation I found this


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> (date (date-value 2008 4 1) 300 "%Y %m %d")
"2008 04 01"


That made me think - Daylight Savings Time issue (March 9th)


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> (date (date-value 2008 3 8) 300 "%Y %m %d")
"2008 03 07"
> (date (date-value 2008 3 9) 300 "%Y %m %d")
"2008 03 08"
> (date (date-value 2008 3 10) 300 "%Y %m %d")
"2008 03 10"
> (date (date-value 2008 3 9 1 0 0) 300 "%Y %m %d")
"2008 03 09"
> (date (date-value 2008 3 8 1 0 0) 300 "%Y %m %d")
"2008 03 08"


It looks like doing historical date conversion doesn't take into consideration daylight savings time.  Also notice that I can't get access to what the timezone was before March 9th and adjust the offset accordingly.



My hackish workaround is to take the time at 3am.  

But I'm hoping there's a better way.  

So finally ... here's a newlisp days-in-month
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(define (days-in-month y m)
  (set 'tmp (date (date-value) 0 "%z"))
  (set 'offset (+ (* (int (1 2 tmp)) 60) (int (3 2 tmp))))
  (if (= "+" (0 1 tmp)) (set 'offset (* -1 offset)))
  (int (date (date-value y (+ m 1) 0 3 0 0) offset "%d"))
)
> (days-in-month 2008 2)
29
> (days-in-month 2007 2)
28
> (days-in-month 2008 3)
31
> (days-in-month 2008 4)
30
#3
newLISP newS / newLISP on Noodles with Nettles
January 03, 2007, 04:21:56 PM
http://newlisp-on-noodles.org/wiki/images/3/3e/Nettlepasta.jpg">



I just released a module for working with the nettle cryptographic library.



http://newlisp-on-noodles.org/wiki/index.php/Nettles">http://newlisp-on-noodles.org/wiki/index.php/Nettles



Enjoy!



PS - I haven't been able to get it to work on Mac OS X. Nettle is in Fink but there's no dylib. If anyone knows how to make libnettle.dylib from libnettle.a I'd appreciate a tutorial in converting. For now it's been tested with Linux only.
#4
newLISP newS / Noodles
November 01, 2006, 01:11:36 PM
johnd and I have decided to publicly release the newLISP on Noodles wiki



http://www.newlisp-on-noodles.org">http://www.newlisp-on-noodles.org



In a nutshell, we want Noodles to be the "Ruby on Rails" of newLISP.



Right now we've got a few place holders for library and module development and some tips 'n' tricks.



Enjoy.



Gord
#5
newLISP in the real world / fork and sleep
May 10, 2005, 04:09:20 PM
Can someone explain to me why the following code does not sleep 5 seconds?

I have a hunch that a signal from the forked child invalidates the sleep - but I have no proof.
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(define (SleepMe x)
  (println "Starting...")
  (fork (dotimes (y 10) (println y)))
  (sleep (* x 1000))
  (println "Why do you not sleep?")
)

(SleepMe 50)


Gord
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