Re: [Tutor] primes (Cautious remark on Python and Scheme)
Hi Danny! Preliminary remark: I know that beautiful and beauty are concepts very seldom applied to computer programs or programming languages. I suppose mainly because they are to a large extent a matter of taste ... Nevertheless: regardeless of the fact that I'm not a very skilled scheme-programmer, for me Scheme is the most beautiful programming language I know, mainly because of the clear and simple concepts which are purely realized. (I do *not* want to discuss here questions like functional versus object-oriented languages etc...) However - Python - for me - is a programming language for the pragmatic lover. Do you consider this expression as self explanatory? Lover -- because it makes so much fun to use it. Pragmatic -- because it is a language for the real world ;-) im*h*o the primes - examples we are just discussing shows, that going *the Python way* may well be more successful or rewarding than trying to translate, traduce, ...er .. adapt Scheme-concepts quasi trying to show that Python is at least as good as Scheme. This is not the question. (I suppose that this also was not your goal?) A deeper question perhaps would be to what degree the content of cs texts depends on the choice of the mainly used language therein. On the contrary - we may learn from this example that Python is a *very* good language in its own right - with carefully chosen concepts and syntax and a very slow, serious and publicly controlled development process resulting in a more and more easily and efficiently usable language. Finally I'd like to stress that your contribution for me was very valuable and constructive - as are most of your innumerable contributions to the discussions on this list. Thanks an regards, Gregor post scriptum: as always when writing not only about technical facts but about opinions and values in English, I'm a bit axious if I was able to express correctly what I wanted to say. Hmmm. Hope that I didn't create any misunderstandings Danny Yoo schrieb: On Thu, 17 Mar 2005, Gregor Lingl wrote: Hi! Who knows a more concise or equally concise but more efficient expression, which returns the same result as [x for x in range(2,100) if not [y for y in range(2,x) if x%y==0]] Hi Gregor, Here is one that's traduced... er... adapted from material from the classic textbook Structure and Interpretation of Computer Programs: ## from itertools import ifilter, count def notDivisibleBy(n): ... def f(x): ... return x % n != 0 ... return f ... def sieve(iterable): ... nextPrime = iterable.next() ... yield nextPrime ... restOfPrimes = sieve(ifilter(notDivisibleBy(nextPrime), iterable)) ... for prime in restOfPrimes: ... yield prime ... primes = sieve(count(2)) primes.next() 2 primes.next() 3 primes.next() 5 primes.next() 7 primes.next() 11 primes.next() 13 primes.next() 17 primes.next() 19 primes.next() 23 ## The neat thing about this code is that it produces an infinite iterator of prime numbers. The original code in Scheme is itself quite concise and quite nice. It is described here: http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-24.html#call_footnote_Temp_455 Best of wishes to you! -- Gregor Lingl Reisnerstrasse 3/19 A-1030 Wien Telefon: +43 1 713 33 98 Mobil: +43 664 140 35 27 Autor von Python für Kids Website: python4kids.net ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] primes (Cautious remark on Python and Scheme)
Concerning my previous posting - perhaps it would suffice to summarize: While Python is a language for the pragmatic lover, Scheme is much more fundamentalistic. (thought-) *PROVOKING*? Gregor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[OT] Re: [Tutor] primes (Cautious remark on Python and Scheme)
Gregor Lingl said unto the world upon 2005-03-18 19:57: Hi Danny! Preliminary remark: I know that beautiful and beauty are concepts very seldom applied to computer programs or programming languages. I suppose mainly because they are to a large extent a matter of taste ... Hi Gregor and all, Though I've not had the time to follow the details of the thread closely, it's stored for future perusal -- I'm really glad you started it, Gregor. But, your comment above caught my eye. import this to see that beauty is embraced by the zen :-) It's been a long day, so I don't feel I am saying this well, but: When not trying to learn Python, I'm a (grad student) philosopher of logic and mathematics. I've thought some about beauty in proof, and hope to think seriously about it one day. Beauty in maths is like what the judge said about pornography -- I can't define it, but I know it when I see it. I've never met a philosopher or a mathematician who could give a compelling (and robust) account of what makes for beauty, but there is widespread convergence of judgements about which proofs are beautiful and which ugly. (This even though taste does enter into it, too.) I think the same is true of (at least academic) computer science. The comp sci people I know at my uni all work in automated-theorem proving, and I know they use their perceptions of beauty as a design guide. And, with my much more limited experience with programming, my judgements that this code is ugly have been pretty reliable in identifying the problematic parts. If it is beautiful, it might be right. If it is ugly, it is likely wrong seems a safe claim. Anyway, all this is to say that I think that what you know above is wrong :-) SNIP post scriptum: as always when writing not only about technical facts but about opinions and values in English, I'm a bit axious if I was able to express correctly what I wanted to say. Hmmm. Hope that I didn't create any misunderstandings Ich kann Deutsch, aber nur ein bischen. I think I'd be a very happy fellow if my German were half as good as your English :-) Best to all, Brian vdB ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
