module factorialp;

import pyd.pyd;
import std.algorithm;
import std.range;
import std.bigint;
import std.parallelism;
import std.datetime;
import std.stdio;

BigInt factorial(int base) {
    auto chsize = base / totalCPUs / 4;
    BigInt result;
    auto starttime = Clock.currTime();
    auto result =
        taskPool.reduce!"a * b"(
            map!(fold!"cast(std.bigint.BigInt)a * b")
                (
                    chunks(
                        iota(1, base + 1),
                        chsize ? chsize : 1
                    )
                )
        );
    writefln("elapsed time = %s", Clock.currTime() - starttime);
    return result;
}

extern(C) void PydMain() {
    def!factorial();
    module_init();
}