Code shared from run.dlang.io. Run with '-unittest'

main.d

void main()
{
    import std.algorithm, std.conv, std.stdio;

    "Starting program".writeln;

    // Sort a constant declaration at Compile-Time
    enum a = [ 3, 1, 2, 4, 0 ];
    static immutable b = sort(a);

    // Print the result _during_ compilation
    pragma(msg, text("Finished compilation: ", b));
}