Re: Re: Better "uniq" idiom?

I have been aware that you can make it faster that way, but I usually don't. All that extra typing hurts my fingers :-)

No not really, but I like to keep oneliners short -- they have a nasty habit of hitting the right margin once what I do gets complicated -- and if I ever care about the performance of a oneliner, chances are it is getting complicated.

Having said that, it occurs to me that you might get the best of both worlds with a slightly different idiom. Compare:

perl -ne'print unless $seen{$_}++'
perl -ne'$seen{$_}++, print unless $seen{$_}'
perl -ne'$seen{$_}||=(print,1)'
[download]

Hey! It's even shorter than the original! We may be onto something here ... or maybe I have just been golfing too much lately ... :-)

Update: Juerd writes for oneliners, I think it's safe to assume print will print succesfully. Well ... I guess it is a good thing you have not seen my one-liners then. But okay, safe or not, it certainly is reasonable. It's not your fault that I am neither :-)

The Sidhekin
print "Just another Perl ${\(trickster and hacker)},"

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Re: Re: Re: Better "uniq" idiom? by Juerd (Abbot) on Mar 21, 2002 at 22:09 UTC
perl -ne'$seen{$_}\|\|=(print,1)' Assuming the print will not fail (and for oneliners, I think it's safe to assume print will print succesfully): `perl -ne'$seen{$_}\|\|=print'` [download] See? print, like many other commands, returns true on success, which allows you to shorten the shortened shortening by another 4 characters! Implementing s/seen/s/: `perl -ne'$s{$_}\|\|=print'` [download] Using symbolic references, assuming no special variable names will be used: `perl -ne'$$_\|\|=print'` [download] I think Perl 6 should have an alias for print that is a single \W character ;) Would be fun for golfing, and could compensate for the needed whitespace with string concats :) U28geW91IGNhbiBhbGwgcm90MTMgY W5kIHBhY2soKS4gQnV0IGRvIHlvdS ByZWNvZ25pc2UgQmFzZTY0IHdoZW4 geW91IHNlZSBpdD8gIC0tIEp1ZXJk	[reply] [d/l] [select]

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Re: Re: Re: Better "uniq" idiom?
by Juerd (Abbot) on Mar 21, 2002 at 22:09 UTC

perl -ne'$seen{$_}||=(print,1)'

Assuming the print will not fail (and for oneliners, I think it's safe to assume print will print succesfully):

perl -ne'$seen{$_}||=print'
[download]

perl -ne'$s{$_}||=print'
[download]

perl -ne'$$_||=print'
[download]

U28geW91IGNhbiBhbGwgcm90MTMgY
W5kIHBhY2soKS4gQnV0IGRvIHlvdS
ByZWNvZ25pc2UgQmFzZTY0IHdoZW4
geW91IHNlZSBpdD8gIC0tIEp1ZXJk

[reply]
[d/l]
[select]