Re: [q-lang-users] Re: Optimizations and tweaks

[Tim H. <q...@st...>]

Dr....@t-... (Albert Graef) writes:

> Tim Haynes wrote:
>> Oh, *excellent* <rubs hands in glee>. Thanks for that. Refs as well? I have
>> much Q to be learning. :)
>
> Also soon to be unleashed upon the unexpecting world: SWIG support! This
> will turn the creation of library interfaces into a no-brainer. But don't
> tell anyone just yet, I'm still testing. ;-) C already works very well, I
> wish I had that when I wrote the clib module ... As soon as I'm satisfied
> with the result of auto-wrapping a huge C++ library like the entire Qt
> it's time for a release again.

Oh wow. If it's really capable of coping with something that size, it'll be
amazing. I'm already wondering about writing a tiny graphical app in Q (an
RSS aggregator with a difference) as it is :)

>> I've implemented memoization on `prime' and `isprime' functions - works
>> first time ;)
>
> Care to post your final algorithm here?

Sure. :)  I think this is the best of all worlds so far:

#!/usr/bin/env q
#! -q
#! -cmain ARGS || quit

def HASH = ref emptyhdict;

public hashed F X;
hashed F X      = get HASH!(F,X) if member (get HASH) (F,X);
                = put HASH (update (get HASH) (F,X) Y) || Y
                    where Y = F X otherwise;

hashed isprime = hisprime;

hisprime N = not (any ((=0).(N mod))) (primes (intsqrt N)) ;

hashed primes = hprimes;

hprimes N        = [2] if N=2; 
                 = [2,3] if N=3; 
                 = [2,3|filter isprime [5,7..N]] otherwise; 

def P=val (ARGS!1);

dump N = strcat [str N, " is ", (str (isprime N)), "\n"];

main ARGS = dump P;


(The reason for `dump' and main being separate is that I was running dump,
and therefore isprime, across a list [(P-10)..(P+10)], for benchmarking
purposes.. :)

You're welcome to use it for docs / consider it GPL'd / whatever's
easiest, as you wish. :)

~Tim
-- 
<http://spodzone.org.uk/>