Simon Forman wrote:
On Sat, Nov 14, 2009 at 5:10 PM, Terry Reedy <tjre...@udel.edu> wrote:
Paul Rubin wrote:
Mark Chu-Carroll has a new post about Go:
http://scienceblogs.com/goodmath/2009/11/the_go_i_forgot_concurrency_an.php
In a couple of minutes, I wrote his toy prime filter example in Python,
mostly from the text rather than the code, which I can barely stand to read.
It ran the first time without error.
def plurals():
i = 2
while True:
yield i
i += 1
def primefilter(src, prime):
for i in src:
if i % prime:
yield i
src = plurals()
while True:
i = next(src)
print(i)
src = primefilter(src, i)
As I commented there
"It stopped at 7877 when it hit the default recursion limit of 1000, which
could easily be increased to get out-of-memory error instead.
I think Google is making a blunder if it moves to another old-fashioned
language whose code is bloated with junky boilerplate that doubles the size.
It would be much better, for instance, to tweak Python, which it has had
great success with, to better run on multiple cores."
Terry Jan Reedy
FWIW,
def plurals():
i = 3
while True:
yield i
i += 2
Of course, in fact, I thought of at the time
def plurals():
i = 6
while True:
yield i-1
yield i+1
i += 6
5,7, 11,13, 17,19, 23,(25-first miss), 29,31, (35-2nd miss),37, 41,43,
47,(49 erd)...Reduced the base cases by another 1/3. I *think* without
measuring, that that compensates for the extra -1,+1. But I was
implementing *Mark's* toy example, and first posted it on his blog, so I
copied his naive version.
Even better, to avoid extra -1, +1
def plurals():
yield 2
yield 3
i = 5
while True:
yield i
i += 2
yield i
i += 4
Of course, testing with primes greater that square root(candidate) is
wasteful, and recusion should be converted to iteration to avoid
recursion limit.
Terry Jan Reedy
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