Explanation of How Hangman Operates

sub cls

Returns nothing.

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

sub get_committer_list

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

    $x //= $y;

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

Next, we use smart matching, ~~, 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 = to perform a readline operation on the filehandle.

sub draw_board

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

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

Now, ~= 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 (~) followed by an equal sign. Which therefore means that

  $output ~= @letters[$i]; 

translates to:

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

sub has_won

In the grep here:

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

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

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

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

sub guess

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

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.

sub draw_hangman

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

## main loop

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

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

ERRATA

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

AUTHOR

Terrence "metaperl" Brannon

Substantial #perl6 help from

  mauke, ninereaons, revdiablo, autrijus, stevan

cpanm Perl6::Pugs

perl -MCPAN -e shell
install Perl6::Pugs