I'd like to convert the following program to 2020 standards (i.e, replace the foreach block with a one-line code). I've tried much and I failed.

This is the code that works (1990s style)

--
import std;

void main()
{
    immutable URL = r"https://raw.githubusercontent.com/CSSEGISandData/COVID-19/master/csse_covid_19_data/csse_covid_19_time_series/time_series_covid19_confirmed_global.csv";
    immutable LOCAL = r"local-file";
    immutable country = "Poland";

    download(URL, LOCAL);

    auto file = File(LOCAL, "r");
    int i = 0;

    foreach(rec; file.byLine())
    {
        auto x = rec.splitter(',').array;

        if (i == 0)
        {
            // Print Header
            writeln(x);
        }
        else if (x[1] == country)
        {
            // Print Country Line
            writeln(x);
            break;
        }

        i++;
    }
}
--

On Tuesday, 31 March 2020 at 04:00:28 UTC, User wrote:
> I'd like to convert the following program to 2020 standards (i.e, replace the foreach block with a one-line code). I've tried much and I failed.

Here is how I'd do it.

Because the program downloads and then reads the local file unconditionally, I replaced it with byLine. This allows it to process the data as it is being downloaded, without first waiting to download everything.

import std;

void main()
{
	immutable URL = r"https://raw.githubusercontent.com/CSSEGISandData/COVID-19/master/csse_covid_19_data/csse_covid_19_time_series/time_series_covid19_confirmed_global.csv";
	immutable country = "Poland";

	URL
		.byLine
		.map!(line => line.splitter(","))
		.enumerate
		.filter!(t => t.index == 0 || t.value.dropOne.front == country)
		.map!(t => t.value)
		.take(2)
		.each!writeln;
}