Posts Tagged ‘D’

Prime sieve

Tuesday, December 11th, 2007

Since I haven’t posted in ages, and D doesn’t get nearly enough love from anyone, have a prime sieve.

This is public domain, I suppose. It’s not very spectacular, and took maybe ten minutes to write, so whatever.

module sieve;
 
import fun;
 
long[] sieveTo(long lim)
{
    long l = 0;
    long[] o; o.length = 100;
    foreach (ref i; o) i = 2;
 
    for (long i = 2; i < lim; i++) {
        if (!o.any( (long p) { return i != 0 && i % p == 0; } )) {
            if (l >= o.length) o.extend();
            o[l++] = i;
        }
    }
 
    o.length = l;
    return o;
 
}
 
private void extend(T)(ref T[] arr)
{
    int l = arr.length;
    arr.length = arr.length * 2;
    for (int i = l+1; i < arr.length; ++i)
        arr[i] = 2;
}

the relevant part of fun.d (where I reimplement the parts of Haskell I miss :v ) is the any function:

bool any(T)(in T[] arr, bool delegate(T) p)
{
    foreach(t; arr)
        if (p(t)) return true;
    return false;
}

All in all, D is surprisingly concise, and nice, and people should use it more.

And it should have Qt bindings for it. :(

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