=head1 Explanation of How Hangman Operates

=head1 sub cls

Returns nothing.

Checks the magical lexical (S02) C<$?OS> against a junction consisting of 3
values. Use the ternary operator C<?? !!> to decide what system command to use
to clear the screen.

=head1 sub get_committer_list

C<err> is the low precedence form of C<//> (S03). C<//> is especially useful
in its assignment form:

    $x //= $y;

To summarize, C<||> and C<or> relate to truth, while C<//> and C<err> relate
to definedness.

Next, we use smart matching, C<~~>, to skip all of the lines from the
beginning of the file which have something other than whitespace.

In the loop that follows:

    for (=$dict) -> $name {

we use the unary C<=> to perform a C<readline> operation on the
filehandle.

=head1 sub draw_board

We look over the numbers which are the indices to the elements of the array 
C<@letters> by forcing the array into numerical context:

    for (0 .. (+@letters - 1)) -> $i {

Now, C<~=> might throw you. You Perl 5'ers are seeing the regexp matching 
operator in reverse. But what you should be seeing is the Perl 6 string
concatenation operator (C<~>) followed by an equal sign. Which therefore 
means that

  $output ~= @letters[$i]; 

translates to:

  $output = $output ~ @letters[$i] ;

=head1 sub has_won

In the C<grep> here:

    @letters == @solution.grep:{ $_ ne '' };

the block beginning with a colon is called an I<adverbial block>.  It is
equivalent with:

    grep(@solutions: { $_ ne '' })

In both cases, C<@solutions> is the invocant, and the block is the argument.

=head1 sub guess

The loop construction (S04) is used without the the statement modifiers 
C<until> or <while> which it can take.

=head1 sub draw_if_greater_than

    sub draw_if_greater_than (Str $char, Int $num) returns Bool { 
        ($number_of_bad_guesses >= $num) ?? $char !! ' ';
    }

The character for blank should be a constant, e.g.:

    my constant $BLANK = ' ';

but it is not implemented yet.

=head1 sub draw_hangman

Here we see function interpolation, i.e. the use of C<{ ... }> blocks
inside strings.

=head1 ## main loop

Note that the list-context C<x> in Perl 5 is now C<xx> in Perl 6:

    @solution = ('' xx +@letters);

=head1 ERRATA

If you read Apocalypse 03, you will see strong motivation for changing the
ternary operator syntax.

=head1 AUTHOR

Terrence "metaperl" Brannon

Substantial #perl6 help from 

  mauke, ninereaons, revdiablo, autrijus, stevan
