load 'file';
load 'environ';
load 'readline';

var history_file = environ.HOME ~ '/.mal_history';

function is_blank(line) {
    return line =~ /^\s*$/;
}

function load_history() {
    try (ex) {
        var content = file_read(history_file);
        var lines = content =~ /[^\n]*/Ag;
        foreach[] line (lines) {
            if (!is_blank(line))
                rl_add_history(line);
        }
    catch FileEx:
        // ignore non-existing or unreadable file
    }
}

function add_to_history(line) {
    rl_add_history(line);
    file_append(history_file, line ~ '\n');
}

function repl(prompt) {
    load_history();

    while(1) {
       var line = rl_readline(prompt);
       if (not defined line)
           break
       if (!is_blank(line)) {
           write(line ~ '\n');
           add_to_history(line);
       }
    }
}

repl('> ');
write('\n');