Errata

the package name is not rakudo-star

should have been

C:\ choco install rakudostar

instead.

Note from the Author or Editor:
Change as noted

There are two code sections that look like this:

put 'Hello Perl 6!';
put 'The time is ', now;

In the second one, remove the final semicolon:

put 'Hello Perl 6!';
put 'The time is ', now

Note from the Author or Editor:
Change as noted

On p8 the bottom example:

loop { state $count = 0; sleep 1; print $count, "\r"; }

is it perhaps missing a ++? as in:

loop { state $count = 0; sleep 1; print $count++, "\r"; }

It just seems a little pointless without the ++.

Note from the Author or Editor:
Change as noted

"You must start your name with a letter or digit"

raku.guide indicates letter or underscore, not digit.

Note from the Author or Editor:
Change as noted

p6doc language/variables gives No such type 'language/variables'

but

p6doc variables seems to give the desired documentation page

Note from the Author or Editor:
Change as noted

The env command is usually available under /usr/bin/env. Only some systems provide /bin/env in addition to /usr/bin/env.

Note from the Author or Editor:
substitute /usr/bin/env for /bin/env as noted

The phrase "For numbers, 0 is False and everything else is True" appears at the end of the second paragraph, and is repeated at the end of the third.

This phrase should only appear once.

Note from the Author or Editor:
Remove the sentence from the second paragraph.

The variable $n needs to be declared with "my".

% perl6
> $n = 10
10
> 7 < $n < 15

ought to be changed to

% perl6
> my $n = 10
10
> 7 < $n < 15

Note from the Author or Editor:
Change as noted.

In the snippet

my Int $number;
put $number2.^name; # Int

the first and the second variable names are different.

They should be the same.

Note from the Author or Editor:
change the second variable name to match the first ($number)

put .numerator, '/', .denominator, ' = ' given $sum;

is missing the final printout of $sum

maybe should be something like:

put .numerator, '/', .denominator, ' = ', $sum given $sum;

Note from the Author or Editor:
Change as noted

The book says:

> Q :q 「This quote \「\」 escapes」
This quote 「 escapes

But it should be:

> Q :q 「This quote \「\」 escapes」
This quote 「」 escapes

Note from the Author or Editor:
Change as noted

put 'hamadryas PERLICUS'.tc;

should be

put 'hamadryas PERLICUS'.tclc;

Note from the Author or Editor:
Change as noted.

Result is True, not False ( 'Hama...'.fc.starts-with: 'hama' )

Note from the Author or Editor:
In second code example from bottom, change to:

> 'Hamadryas perlicus'.fc.starts-with: 'hama'
True

using the code

if $answer { 'You chose <', $answer, '>' }

has an interesting side effect. It looks like

put do { 'You chose <', $answer, '>' }

puts a single space between the arguments:

> $answer = ' X '.trim;
X
> put do { 'You chose <', $answer, '>' }
You chose < X >
> put 'You chose <', $answer, '>'
You chose <X>

This makes it look (erroneously) like .trim compresses leading and trailing spaces down to single spaces, not removing them entirely, and yielding the following output when the script is modified to use .trim:

% perl6 prompt.p6
What's your favorite animal? Butterfly
You chose < Butterfly >

An easy way to fix this would be to concatenate them using ~, thus changing the 3rd line of the script to

if $answer { 'You chose <' ~ $answer ~ '>' }

This way, when the program is changed to use .trim, you get the following result:

% perl6 prompt.p6
What's your favorite animal? Butterfly
You chose <Butterfly>

Note from the Author or Editor:
Changed as noted

The warning "You cannot make an empty List with $(): that's just Nil" only applies to version 6.c of the Raku programming language. From Rakudo 2018.10 on $() hasn't got any special meaning and makes an empty list (unless "use v6.c" is effective).

Note from the Author or Editor:
Remove the warning box on page 90.

The second code sample reads

my $countdown = <1 2 3 4 5>.reverse.eager;
put $countdown.^name; # Seq
put $countdown.elems; # 5

It should read

my $countdown = <1 2 3 4 5>.reverse.eager;
put $countdown.^name; # List
put $countdown.elems; # 5

Note from the Author or Editor:
Change as noted

Some spacing needed in "[POSITION]is a postcircumfix..."

Note from the Author or Editor:
Change as noted

In the sentence "It takes a starting index, a length, and the items to remove from the list." about .splice, doesn't the last parameter in .splice specify the items with which to replace the removed elements? From the doc:

multi method splice(Array:D: $start = 0, $elems?, *@replacement --> Array)

Deletes $elems elements starting from index $start from the Array, returns them and replaces them by @replacement.

Note from the Author or Editor:
change "remove from list" to "add to list"

The code sample reads:

my $list = ( 1; 'Hamadryas'; 'a', 'b' );
put $list.elems; # 3
say $list; # (1 2 (a b))
put $list.[0].^name; # Int
put $list.[1].^name; # Str
put $list.[*-1].^name; # List

It should read:

my $list = ( 1; 'Hamadryas'; 'a', 'b' );
put $list.elems; # 3
say $list; # (1 Hamadryas (a b))
put $list.[0].^name; # Int
put $list.[1].^name; # Str
put $list.[*-1].^name; # List

Note from the Author or Editor:
Change as noted

The page says:

Each sublist has three elements:

((1 a ????)(2 b ????)(3 ????))

but the last sublist only shows two. It should say

Each sublist has three elements:

((1 a ????)(2 b ????)(3 c ????))

Note from the Author or Editor:
Change as noted.

"What’s actually in $result?"

should read

"What’s actually in $value?"

Note from the Author or Editor:
Change as noted

Misindented.

Note from the Author or Editor:
Indent like so:


Indent like so, with everything inside the try { ... } moved over four spaces:

try {
CATCH {
when X::MyException { put 'Caught a custom error' }
}
my-own-error();
}

The snippet says

my $result = do-something();
if $result { ... }
my $did-it-work = ?$results;

but it should probably say

my $result = do-something();
if $result { ... }
my $did-it-work = ?$result;

Note from the Author or Editor:
change as noted

"It’s probably easiest to represent it as a decimal number"

should read

"It’s probably easiest to represent it as an octal number"

Note from the Author or Editor:
Change as noted

Misplaced comma in "write, this".

Note from the Author or Editor:
should be "as I write this," in note

The comment reads:

# ((Any) perlicus Sostrata Junonia)

However, 'perlicus' should be removed:

# ((Any) Sostrata Junonia)

Note from the Author or Editor:
This is actually on page 105 (Chapter 6, "Changing a Single Element")

the third to last code block should read:

my $butterflies = ( $, 'Sostrata', 'Junonia' );
say $butterflies; # ((Any) Sostrata Junonia)

In the code snippet:

my Buf $buffer = $fh->read( $count );

the pointy block arrow (->) is used to invoke the `read` method. However, a dot (.) should be used instead.

Note from the Author or Editor:
Change

my Buf $buffer = $fh->read( $count );

to


my Buf $buffer = $fh.read( $count );

The variable names read better as @permissible... instead of @permissable...

Note from the Author or Editor:
Change all instances of @permissable to @permissible

%color should be %color-name-to-rgb.

Note from the Author or Editor:
Change all instances of %color on that page to %color-name-to-rgb

multi subsomething ( $a ) { put "One argument"; }
multi subsomething ( $a, $b ) { put "Two arguments"; }

should read

multi sub something ( $a ) { put "One argument"; }
multi sub something ( $a, $b ) { put "Two arguments"; }

Note from the Author or Editor:
change as noted

The example on the previous page is:
"You call .reverse on a List to flip the list around. When you call List methods it just works:
my $countdown = <1 2 3 4 5>.reverse;
put $countdown.^name; # Seq
put $countdown.elems; # 5”

On the next page the first line is "The result isn’t actually a Seq, but in most common cases that isn’t important."
I think it should say that the result *IS* actually a Seq.

Note from the Author or Editor:
Change to read "The result is actually a Seq"

The '+' should be a '*'.

Note from the Author or Editor:
Change as noted to "3 * 3"

operaters -> operators

The current sentence is "This like your basic number-guessing program, but you have to make two sets of comparisons."

It should probably be "This is like your basic number-guessing program, but you have to make two sets of comparisons." The word "is" should be added after the word "This".

Note from the Author or Editor:
Change as noted.

sub MAIN ( $thingy1, $thingy2 ) { put '1: ', $thingy1; put '2: ', $thingy1; }

You probably intended:

sub MAIN ( $thingy1, $thingy2 ) { put '1: ', $thingy1; put '2: ', $thingy2; }

Note from the Author or Editor:
Change as noted

Subset::Common

*** should be

Subsets::Common

Note from the Author or Editor:
Change as noted