What is the best way to process this list
in [Lisp]
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From: mdj on 4 Jan 2010 00:54 On Jan 4, 3:22 pm, Kenneth Tilton <kentil...(a)gmail.com> wrote: > > False. Structures are not always faster than plist. Notaby, > > implementations may typecheck the structure object, which slows > > structure accessors so much that plist up to 5 or even more slots is > > faster. > > Rubbish! What crappy implementation are you imagining for these > incredibly slow defstructs (by which I mean which Lisp and how do they > implement defstructs by default? Lemme see some timings! Unless the structures were implemented with conses this seems almost impossible, since a slot access can be compiled out to nothing more than indexed addressing! And the type check is what, a single compare ?
From: Kenneth Tilton on 4 Jan 2010 01:33 mdj wrote: > On Jan 4, 3:22 pm, Kenneth Tilton <kentil...(a)gmail.com> wrote: > >>> False. Structures are not always faster than plist. Notaby, >>> implementations may typecheck the structure object, which slows >>> structure accessors so much that plist up to 5 or even more slots is >>> faster. >> Rubbish! What crappy implementation are you imagining for these >> incredibly slow defstructs (by which I mean which Lisp and how do they >> implement defstructs by default? Lemme see some timings! > > Unless the structures were implemented with conses this seems almost > impossible, since a slot access can be compiled out to nothing more > than indexed addressing! Yep. > And the type check is what, a single > compare ? > Type-checking is for Java/C++ wusses! I always get a kick out of struct accessors working on the wrong struct when I screw up. Same thing with coding the wrong copier: copies fine! kt -- http://thelaughingstockatpngs.com/ http://www.facebook.com/pages/The-Laughingstock/115923141782?ref=nf
From: mdj on 4 Jan 2010 03:24 On Jan 4, 4:33 pm, Kenneth Tilton <kentil...(a)gmail.com> wrote: > Type-checking is for Java/C++ wusses! I always get a kick out of struct > accessors working on the wrong struct when I screw up. Same thing with > coding the wrong copier: copies fine! Well, 'correct' programs don't need it :-) I like the "lisp way" of providing runtime checking until I decide I need the speed more than the belt ...
From: Pillsy on 4 Jan 2010 09:58 On Jan 3, 12:34 am, Kenneth Tilton <kentil...(a)gmail.com> wrote: [...] > I suggest you write the code you are writing now and not the code you > might write someday. [...] I nominate this for the Kenny fortune file. Cheers, Pillsy
From: Pascal J. Bourguignon on 4 Jan 2010 10:55
Kenneth Tilton <kentilton(a)gmail.com> writes: > Pascal J. Bourguignon wrote: > >>> Using a plist is not the lay to go. Use defstruct. Simpler than a >>> plist, really, and massively more efficient. >> >> False. Structures are not always faster than plist. Notaby, >> implementations may typecheck the structure object, which slows >> structure accessors so much that plist up to 5 or even more slots is >> faster. > > Rubbish! What crappy implementation are you imagining for these > incredibly slow defstructs (by which I mean which Lisp and how do they > implement defstructs by default? Lemme see some timings! > > kt Existance proof: C/USER[11]> (defstruct ss a b c d e) SS C/USER[12]> (let ((s (make-ss :a 42))) (time (loop :repeat 100000 :do (ss-a s)))) Real time: 0.494208 sec. Run time: 0.464029 sec. Space: 804400 Bytes NIL C/USER[13]> (defstruct (sl (:type list)) a b c d e) SL C/USER[14]> (let ((s (make-sl :a 42))) (time (loop :repeat 100000 :do (sl-a s)))) Real time: 0.489189 sec. Run time: 0.424026 sec. Space: 804400 Bytes GC: 1, GC time: 0.012001 sec. NIL C/USER[15]> (values (lisp-implementation-type) (lisp-implementation-version)) "CLISP" ; "2.41 (2006-10-13) (built on thalassa.lan.informatimago.com [192.168.1.198])" C/USER[17]> (disassemble 'ss-a) Disassembly of function SS-A (CONST 0) = SS (CONST 1) = 1 1 required argument 0 optional arguments No rest parameter No keyword parameters 5 byte-code instructions: 0 (CONST&PUSH 0) ; SS 1 (LOAD&PUSH 2) 2 (CONST&PUSH 1) ; 1 3 (CALLS2 47) ; SYSTEM::%STRUCTURE-REF 5 (SKIP&RET 2) NIL C/USER[18]> (disassemble 'sl-a) Disassembly of function SL-A 1 required argument 0 optional arguments No rest parameter No keyword parameters 3 byte-code instructions: 0 (LOAD 1) 1 (CAR) 2 (SKIP&RET 2) NIL C/USER[19]> -- __Pascal Bourguignon__ http://www.informatimago.com/ |