paultcochrane/P01-scottp.html

## P01-scottp.html
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use v6;

=begin pod

=TITLE P01 - Find the last box of a list.

=AUTHOR Scott Penrose

=head1 LISP

    P01 (*) Find the last box of a list.
    Example:
    * (my-last '(a b c d))
    (D)

Note that, in LISP-speak, the last &quot;box&quot; is the last one-element sublist of
the list. In perl6, a single element can generally be used as a list and
vice versa; as a result, this example does not distinguish between a single
element and a list containing a single element.

=head1 Example:

    &gt; say my_last &lt;a b c d&gt;;
    d

=end pod

# a. One line example:
#       &lt;&gt; can be used to generate an array, similar to perl 5 - qw&lt;a b c d&gt;
#       [] is used to select the element number
#       * means the number of elements
#       say is like print to stdout with a new line
#       .say can be called as everything is an object
&lt;A B C D E F&gt;[* - 1].say;

# b. Subroutine example
#       @l lists can be passed in as parameters - no need to use references
#       .elems - is the number of elements, this time called on the object
#       say called in procedure form
sub my_last(@l) {
        return @l[@l.elems - 1];
}
say my_last(&lt;A B C D&gt;);

# c. Pop like perl5
#       pop the last element off, which also returns it
#       say either way
say &lt;X Y Z&gt;.list.pop;
&lt;X Y Z&gt;.list.pop.say;

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	<pre id='vimCodeElement'>
	use v6;

	=begin pod

	=TITLE P01 - Find the last box of a list.

	=AUTHOR Scott Penrose

	=head1 LISP

	P01 (*) Find the last box of a list.
	Example:
	* (my-last '(a b c d))
	(D)

	Note that, in LISP-speak, the last "box" is the last one-element sublist of
	the list. In perl6, a single element can generally be used as a list and
	vice versa; as a result, this example does not distinguish between a single
	element and a list containing a single element.

	=head1 Example:

	> say my_last <a b c d>;
	d

	=end pod

	# a. One line example:
	# <> can be used to generate an array, similar to perl 5 - qw<a b c d>
	# [] is used to select the element number
	# * means the number of elements
	# say is like print to stdout with a new line
	# .say can be called as everything is an object
	<A B C D E F>[* - 1].say;

	# b. Subroutine example
	# @l lists can be passed in as parameters - no need to use references
	# .elems - is the number of elements, this time called on the object
	# say called in procedure form
	sub my_last(@l) {
	return @l[@l.elems - 1];
	}
	say my_last(<A B C D>);

	# c. Pop like perl5
	# pop the last element off, which also returns it
	# say either way
	say <X Y Z>.list.pop;
	<X Y Z>.list.pop.say;

	# vim: expandtab shiftwidth=4 ft=perl6
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