Started picking up D recently. I wrote an application to create journal entries (text files) based on user input.

//this program will write to files. It should be able to read them.
//implement a command interface?
import std.stdio;
import std.string;
import std.datetime;
import fileio = std.file;
import std.conv;

enum Commands {exit = "EXIT", create = "CREATE"};

string menuText(){
    return "\nType a command:\n\t- create\n\t- exit\n>";
}

void checkJournalEntriesFolder(){
    string path = "journalEntries/";
    if(fileio.exists(path) == 0){
        writeln("Creating a journalEntries folder for you.");
        fileio.mkdir(path); 
    }
}

string getFileName(){
    return "entry_" ~ std.conv.to!string(stdTimeToUnixTime(Clock.currStdTime())) ~ ".txt";
}

int main(string[] argv)
{
    writeln("\nWelcome to myJournal.");
    checkJournalEntriesFolder();
    string mode = "COMMAND";
    char[] buf;
    Commands command;
    while (mode != "EXIT"){
        while (mode == "COMMAND"){
            string journalContent;
            write(menuText);
            stdin.readln(buf);
            switch(toUpper(buf[0..$-1])) // cut off the /n at the end of the buffer.
            {
                case command.exit:
                    {
                        mode = "EXIT";
                        writeln("Oh, I'll exit.");  
                        break;
                    }
                case command.create:
                    {
                        writeln("create journal entry selected");
                        mode = "CREATE";
                        //create file
                        writeln("You are now typing in your journal.");
                        writeln("To exit this file, type #EOF");
                        writeln("----------------------------");
                        break;
                    }
                default:
                    {
                        writeln("\nunrecognized command");                  
                    }
            }

            while (mode == "CREATE") {
                stdin.readln(buf);
                if(buf[0..$-1] == "#EOF"){
                    writeln("----------------------------");            
                    mode = "COMMAND";
                    checkJournalEntriesFolder(); // double check, in case the user deleted it.
                    string filename = "journalEntries/" ~ getFileName;
                    fileio.write(filename, journalContent[0..$-1]); //Dont include the blank line.
                    writeln("File Saved.");
                } else {
                    journalContent ~= buf;  
                }
            }
        }
    }
    return 0;
}

Possible Improvements:

1. Maybe be able to move throughout the document once it is open (right now if you hit enter, you cannot move to the previous line).
2. Make command / insert mode more like vi.
3. Edit existing files.

I am very new to D, so I expect this code will be tore up. I've done some C++, but it has been a while.