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author | Kartik K. Agaram <vc@akkartik.com> | 2021-10-19 21:38:48 -0700 |
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committer | Kartik K. Agaram <vc@akkartik.com> | 2021-10-22 19:24:44 -0700 |
commit | 74f8cd15bb43110973deffdeb9dd229797e5b328 (patch) | |
tree | 12d6b5475a786eacf7a5a79b03b2b85621578ec6 /test/sieve.lua | |
download | teliva-74f8cd15bb43110973deffdeb9dd229797e5b328.tar.gz |
new fork of Lua 5.1
https://www.lua.org
Diffstat (limited to 'test/sieve.lua')
-rw-r--r-- | test/sieve.lua | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/test/sieve.lua b/test/sieve.lua new file mode 100644 index 0000000..0871bb2 --- /dev/null +++ b/test/sieve.lua @@ -0,0 +1,29 @@ +-- the sieve of of Eratosthenes programmed with coroutines +-- typical usage: lua -e N=1000 sieve.lua | column + +-- generate all the numbers from 2 to n +function gen (n) + return coroutine.wrap(function () + for i=2,n do coroutine.yield(i) end + end) +end + +-- filter the numbers generated by `g', removing multiples of `p' +function filter (p, g) + return coroutine.wrap(function () + while 1 do + local n = g() + if n == nil then return end + if math.mod(n, p) ~= 0 then coroutine.yield(n) end + end + end) +end + +N=N or 1000 -- from command line +x = gen(N) -- generate primes up to N +while 1 do + local n = x() -- pick a number until done + if n == nil then break end + print(n) -- must be a prime number + x = filter(n, x) -- now remove its multiples +end |