Perl 6 Tutorial

Posted by Derek Banas on Jan 19, 2019 in Web Design | 0 comments

This tutorial is a 400 page Perl 6 tutorial condensed down into 1 video. Perl 6 is a get it done fast utility language. I’d say it is the most popular utility language. The newest version ads a ton of tools to the original Perl.

I cover Data Types, Conditionals, Strings, Interpolation, Looping, Arrays, Sequences, Maps, Hashes, Subroutines, Recursion, Exceptions, File IO, Shell, Classes, Inheritance, Roles, Regular Expressions, Grammars and more.

If you find tutorials like this useful, consider turning off Ad Blocking software. I only use one 5 second skippable ad during this entire 1 1/2 hour video. I’d greatly appreciate it if you don’t block it. Thank you 🙂

Cheat Sheet / Transcript

# Install : https://www.rakudo.org/files/star/third-party

#`( multiline or inline
comment
)

# Most data in Perl 6 are objects

# ---- BASICS ----

# Output the string + newline
put 'Hello World';

# Receive user input and save to the variable $name
# my declares a variable
# The sigil $ comes before the variable name
# if you want the value to be changeable (mutable)
my $name = prompt "What's your name? ";
put "Hello $name";

# say normally provides the same output as put
# but it may abbreviate it
put 1 .. 10;
say 1 .. 10;

# print doesn't add a newline
print "No newline";

# ---- VARIABLES ----
# Variable names start with a letter or number
# and can contain underscores, hyphens and
# apostrophes

# You can declare an immutable (unchangeable)
# variable with \
my \pi = 3.1415;
# This would cause an error -> pi = 6;

# You can define types or not
# Common types : Bool, Int, Num (float),
# Real (Non-complex number), Str, Date
my Int $x;
# This would cause an error -> $x = "Dog";

my $y = 6;
$y = "Dog";

# The binding operator creates an alias to
# a variable
my $z := $y;
put $z;

# Booleans are True or False
# 0 is considered false everything else is true
my Bool $can-vote = True;
put $can-vote;

# You can use exponential notation
my $thousand = 1e3;

# Show types
put "10 : ", 10.^name;
put "10.5 : ", (10.5).^name;
put "\"10\" : ", "10".^name;

# Convert int as unicode to character
say '65'.chr;

# Convert numbers to strings
say "Type : ", (10.Str).^name;

# Convert strings to numbers
say "Type : ", (+"123").^name;

# Auto casting works
say "1 + 2 = ", "1" + 2;

# ---- MATH ----
# You can use common math functions
# This is another way to format output
# %d Integers, %f Floats, %s
say (5 + 4).fmt("5 + 4 = %d");
say (5 - 4).fmt("5 - 4 = %d");
say (5 * 4).fmt("5 * 4 = %d");

# Format float with 2 decimals
say (5 / 4).fmt("5 / 4 = %.2f");
say (5**4).fmt("5^4 = %d");

# Adding fractions
say (1/4 + 1/2).fmt("1/4 + 1/2 = %.2f");

# Generate random number between 0 and 20
say "Random : ", 20.rand.Int;

# Generate random value from range 5 to 20
say "Random Range : ", (5..20).rand.Int;

# You can expect 15 digits of precision
my $floatNum = 1.111111111111111111111111111111111111;
my $floatNum2 = 1.111111111111111111111111111111111111;
say "Big Float : ", $floatNum + $floatNum2;

# With math functions you can normally use
# funcName(), or attr.funcName
say "(-1).abs = ", (-1).abs;
say "1.exp = ", (1).exp; # e to the power of
say "sqrt(9) = ", sqrt(9);
say "log(2) = ", log(2);
say "log10(2) = ", log(100);
say "round(2.45) = ", round(2.45);
say "floor(2.45) = ", floor(2.45);
say "ceiling(2.45) = ", ceiling(2.45);

say "sin(0) = ", sin(0);
say "cos(0) = ", cos(0);
say "tan(0) = ", tan(0);
say "asin(0) = ", asin(0);
say "acos(0) = ", acos(0);
say "atan(0) = ", atan(0);
say "cotan(0) = ", cotan(0);
say "acotan(0) = ", acotan(0);
say "sinh(0) = ", sinh(0);
say "cosh(0) = ", cosh(0);
say "tanh(0) = ", tanh(0);
say "asinh(0) = ", asinh(0);
say "acosh(0) = ", acosh(0);
say "atanh(0) = ", atanh(0);
say "atan2(100) = ", atan2(100);

# ---- CONDITIONALS ----
# Conditional Operators  > < >= <= == !-
# Logical Operators : && and, || or, ! not

my $age = 12;
if $age >= 5 && $age <= 6 {
  put "Go to Kindergarten";

  # Shortcut chained comparison
} elsif 7 <= $age <= 13 {
  put "Go to Middle School";
} elsif $age >= 14 && $age <= 18 {
  put "Go to High School";
} else {
  put "Stay Home";
}

# Execute only if true
put 'Old enough for school' if $age >= 5;

# Execute if condition is false
my $k = 0;
unless $k == 5 {
  put $k;
}

# Ternary operator : If true use 1st
# otherwise use 2nd as output
put 'Can vote : ', $age >= 18 ?? 'True' !! 'False';

# ---- STRINGS -----
# Create a string
my $str1 = "Hello";

# You can use variables in output with ""
say "$str1";

# Use quotes by escaping
# \n, \t, \r, \b, \a, \f
say "I like \"quotes\"";

# Number of characters
say "Num : ", $str1.chars;

# Does it have a value
say "Has Value : ", ?$str1;

# To use protected characters surround
# the output with Q and delimiters
say Q/$str1 is ok here/;

# You can also use single quotes
say '$str1 is ok here';

# Concatenate STRINGS
say "one " ~ "string";

# Join also concatenates and puts the first
# string between the next 2 or more
my $str2 = join " ", "a", "long", "string";
say $str2;

# Multiline strings
my $str3 = q :heredoc/END/;
I go
for
many
lines
END
say $str3;

# Does a string contain a string
say "Long? ", $str2.contains("long");

# Add fc to make it case insensitive
say "Long? ", $str2.fc.contains("long");

# Get index where you have a match
my $sI = $str2.index("long");

# Get a substring starting with index 0
# You can often use : instead of ()s with functions
say $str2.substr: $sI, 5;

# Trim whitespace
# Also .trim-leading & .trim-trailing
say "Bye whitespace : ", "     abc   ".trim;

# Lowercase, uppercase, titlecase
say "ABC".lc;
say "abc".uc;
say "abc".tclc;

# Are strings equal
say "Dog".lc eq "dog";

# Greater than is based on alphabetical
# order and uppercase > Lowercase
# Also there is lt
say "GT : ", "abc" gt "d";

# Remove last character
say "abc".chop;

# Remove a newline
say "abc\n".chomp;

# Use variables without spaces
say "{$str1}, Derek";

# Code in strings
say "5 * 4 = {5*4}";

# Use interpolation only between braces
say q :c "\n 1 + 2 = {1+2}";

# Get character by Code
say "\x[40]";

# Duplicate strings
say $str1 x 5;

# Split based on delimiter
say split(', ', "a, b, c");

# Split using Regex
say split(/<[;,]>/, "a,b;c");

# Split using another Regex
say "a b c".split: / \s /;

# Replace matches
my $str5 = "Derek is terrible";
put $str5.subst: /terrible/, 'Awesome';

# ---- LOOPING ----
# Execute as long as a condition is true
loop (my $i = 1; $i < 20; $i++){

  # Print only even numbers
  if $i mod 2 == 0 {
    put $i;

    # Like continue in other languages
    next;
  }
  if $i >= 10 {

    # Jumps out of loop like break
    last;
  }
}

# Print 0 .. 4
loop {
  # Marking this as state sets the value
  # only one time
  state $j = 0;

  # Print and then add 1
  put $j++;

  # Leave loop when true
  last if $j == 5;
}

# While loop
my $i1 = 0;
while $i1 < 5 {
  put $i1++;
}

# Repeat while executes once and then checks
# the condition
repeat while $i1 < 5 {
  put $i1++;
}

loop {
  state $k = 0;
  put $k++;
  last if $k >= 5;

  # Phasers run at the beginning and
  # end of a loop
  FIRST {say "Starting"}
  LAST {say "Ending"}
}

# ---- BLOCKS ----
# You can store blocks of Code
# $_ represents a passed parameter
my $sayHello := { say "Hello $_"};
$sayHello("Derek");

# Use multiple parameters
my $addNums := {$^a + $^b};
say $addNums(1,2);

# You can use Thunks (*) to create closures
# or Whatever codes
my $plus2 = * + 2;
say $plus2(5);

# Subsets can be used to create data types
# that only hold evens for example
subset EvenInt of Int where { $^a mod 2 == 0 };
my EvenInt $eVal = 4;
say $eVal;

# ---- LISTS & ARRAYS ----
# An immutable series of values
my $l1 = List.new: 1, 2, 3;

# Using @ instead of $ provides for shortcuts
# and you create an array thats values can
# be changed
my @l2 = (1, 2, 3);

# Get number of values
say $l1.elems;
say @l2.elems;

# Create a list with values separated by
# spaces
my @l3 = <Mark Sally Paul Sam>;
say @l3.elems;

# Get a value by index
put @l3[0];

# Get a range of values
put @l3[0, 1];

# Change a value
@l3[2] = "Pam";

# Shift off the 1st array element
put @l3.shift;

# Shift a new value on the front
@l3.unshift: <Peter Pat>;

# Pop off the last
put @l3.pop;

# Push items onto the end
@l3.push: <Zack>;

# Splice off values by index
@l3.splice: 0, 2;

# Search for a match
say "Pam : ", @l3.grep("Pam");

# Filter a list
say "Evens ", (1..10).grep: {$_ %% 2};

# Cycle through list with for
for @l3 {
  # $_ is the topic variable
  say "$_";
}

# Get multiple values at once
for @l3 -> $x, $y {
  say "$x $y";
}

# Get key and index
for @l3.kv -> $index, $item {
  say "index $index : item $item";
}

# Sort lists
say sort @l3;

# Create a list of lists
my $l4 = ( <1 2>, <3 4> );
say "00 : ", $l4[0][0];

# Combine 2 lists into one
say zip( <a b>, <1 2>);

# Declare 2 variables at once
my ($val2, $val3) = <a b>;

# Store variables in lists without commas
my $l5 = <<$val2 $val3>>;
put $l5;

# Output with delimiters
put $l5.join(', ');

# Turn a string into an array
# .comb creates a list of characters
my $str4 = "a b c d";
my $l6 = $str4.words;
put $l6;

# Reverse list
put $l6.reverse;

# Maps allow us to transform each element of
# an array (Multiply every value by 2)
my @l7 = 1, 2, 3;
my @map1 = map { $_ * 2 }, @l7;
say @map1;

# Add 2 lists with a hyperoperator
# You can use -, *, /
my @l8 = 4, 5, 6;
say @l7 <<+>> @l8;

# ---- RANGES ----
# You can create ranges of values as
# long as they are in order 1,2,3 a,b,c
# Ranges are not lists
my $r1 = 1 .. 5; # Not 5 .. 1

# Turn a range into a list
my $rl1 = $r1.List;

# Exclude left or right most value
my $r2 = 1 ^.. 5;
my $r3 = 1 ..^ 5;

# ---- SEQUENCES ----
# Sequences are lists that defer the
# creation of values and then doesn't
# store them
my $seq1 := 1 ... 10;

# Sequences can count down
my $seq2 := 10 ... 1;

# They can be created using an algorithm
# Fibonacci series : 1,1,2,3,5,8,13,
my $fib := 0, 1, -> $a, $b { $a + $b } ... *; 1;
put $fib[^10].join(', ');

# Check for lazy lists
put "Lazy : ", $fib.is-lazy;

# ---- SETS ----
# Sets are lists with no duplicates
my $mySet = set(1,2,3,3);
say $mySet.elems;

# ---- MAPS ----
# Maps are immutable lists of ky value pairs
my $japFam = Map.new:
  'Dad', 'Otousan',
  'Mom', 'OKaasan',
  'Son', 'Oniisan',
  'Daughter', 'Oneesan';

# Get value with key
say $japFam<Dad>;

# Check if exists
say $japFam{'Mom'}:exists;

# Get keys and values
for $japFam.kv -> $key, $item {
  put "$key => $item";
}

# ---- HASHES ----
# Mutable maps
my $japColor = Hash.new:
  'Blue', 'Aoo',
  'Red', 'Aka',
  'Green', 'Midori';

# Change a value
$japColor<Blue> = 'Ao';

# Delete kv
$japColor<Blue>:delete;

# Add kv
$japColor<White> = "Shiro";

# Get KVs
for $japColor.kv -> $key, $item {
  put "$key => $item";
}

# ---- SUBROUTINES / FUNCTIONS ----
# Subroutines use return to return values

# sub name (arguments with or without types)
# You can give default values if you want
sub addNums2 ($a = 1, $b = 1){
  return $a + $b;
}
say "1 + 3 = ", addNums2(1,3);

# Arguments can be optional
sub giveMe ($arg?){
  return $arg;
}
say giveMe();
say giveMe(1);

# Store function in a variable
my &sub1 = &addNums2;
say &sub1(1,3);

# Use a slurpy parameter to accept an
# unknown number of arguments
sub addNums3(*@nums){
  state $sum = 0;
  for @nums -> $num {
    $sum = $sum + $num;
  }
  return $sum;
}
say "Sum : ", addNums3 1, 2, 3, 4 ;

# Return multiple values
sub nextTwo($a){
  return $a + 1, $a + 2;
}
say nextTwo(1);

# You can pass a function as a value
# for example to square values in a list
sub square($a){ $a * $a };
my @squaredList = map &square, 1..5;
say join ', ', @squaredList;

# Recursion is when a function calls itself
# Calculate a factorial
sub factorial($a){
  if ($a == 1) {
    return 1;
  } else {
    return $a * factorial($a - 1);
  }
}
say factorial(4);
# 1st : result = 4 * factorial(3) = 4 * 6 = 24
# 2nd : result = 3 * factorial(2) = 3 * 2 = 6
# 3rd : result = 2 * factorial(1) = 2 * 1 = 2

# ---- EXCEPTION HANDLING ----
# We can set up our code to catch errors

# Surround problematic code with try
try {
  # my $ans = (10 %% 0);

  # Throw your own exception
  die 'Bad Stuff';

  # List exceptions to catch here
  CATCH {
    # $_ stores the error message
    when X::Numeric::DivideByZero {
      say "Error : $_";
    }
    default {
      say "Default : $_";
    }
  }
}

# ---- FILE I/O ----
# Create a file for writing
my $f1 = open "mydata", :w;

# Write text to it
$f1.print("file stuff\n");
my $myName = "Derek";
$f1.printf("My name is %s\n", $myName);

# Close file
$f1.close;

# spurt opens, writes and closes the file
# Remove :append to overwrite
spurt "mydata", "spurts stuff\n", :append;

# Read from a file
my $f2 = open "mydata", :r;
my $myData = $f2.slurp;
say $myData;
$f2.close;

# ---- FILE MANIPULATION ----
# Check if file exists
if "mydata".IO.e {
  say "Exists";

  # When was file edited
  say "mydata".IO.modified.DateTime;
  # Read
  say "mydata".IO.accessed.DateTime;
  # Size
  say "mydata".IO.s;
}

# Rename file
rename "mydata", "mydata2";

# Copy file
copy "mydata2", "mydataBU";

# Make a directory
mkdir "Perl Stuff";

# Does directory exist
say "Perl Stuff".IO.d;

# Get directory listing
say dir;

# Remove empty directory
rmdir "Perl Stuff" or die "$!";

# You can run any shell commands
shell('ls -l');

# Store the result of the command
my $shellOP = Q:x{ls -l};

# ---- GRABBING DATA & MODULES ----
# zef is used to install modules that
# provide premade functions and such
# Modules : modules.perl6.org
# Install Popular : zef install Task::Popular

# Install HTTP::UserAgent with
# zef install HTTP::UserAgent

# Used to fetch data
use HTTP::UserAgent;
my $uA = HTTP::UserAgent.new;

# How long to wait
$uA.timeout = 10;

# The URL
my $url = "http://www.gutenberg.org/cache/epub/58670/pg58670.txt";

# See if you can get the data
my $response = $uA.get($url);

my $dW;

# Get data or fail
if $response.is-success {
    $dW = $response.content;
} else {
    die $response.status-line;
}

# Output 10 lines
for $dW.lines(10) -> $text {
  say $text;
}

# ---- CLASSES ----
# Classes simulate real world objects by
# defining attributes and capabilities (methods)

class Animal {

  # Create a private attribute with $!
  has $!name = '';

  # Public with $. (Make read/writable)
  # Define data type or don't
  has Real $.height is rw = 0.0;
  has $.weight is rw = 0.0;

  # Constructor that is called when an
  # object is created
  # The ! after name requires its value
  method BUILD(:$name!, :$height, :$weight) {
    $!name = $name;

    # Handle if values aren't passed
    if $height {
      $.height = $height;
    } else {
      $.height = 0;
    }

    if $weight {
      $.weight = $weight;
    } else {
      $.weight = 0;
    }
  }

  # Provides access to the name (Getter)
  method name { $!name; }

  # You could make name mutable
  # method name is rw { $!name; }

  # Self provides a way to refer to an object
  method info {
    return "{self.name} is {self.height}cms tall and
    {self.weight}kgs";
  }

  # This is an abstract method subclasses
  # will implement
  method makeSound { !!! }

}

# Create an Animal
my $spot = Animal.new:
:name('Spot')
:height(63)
:weight(40);

# Get the name value
say $spot.name;

# This would throw an error without is rw
# $spot.name = 'dog';

$spot.height = 63.5;
$spot.weight = 35.5;
say $spot.info;

# ---- INHERITANCE ----
# Inheriate methods and attributes from Animal
class Dog is Animal {
  has $.sound is rw = "Woof";

  # Overwrite method
  method info {
    # callsame executes the superclass function
    # with the same name
    my $origMsg = callsame;
    # Combine the strings with ~
    return $origMsg ~ " and says {self.sound}";
  }

  # Implement the abstract method
  method makeSound {
    return "{self.name} says {self.sound}";
  }
}

my $doug = Dog.new:
:name('Doug')
:height(63);
say $doug.name;
say $doug.weight;
say $doug.info;

# ---- ROLES ----
# You can add capabilities to objects
# with roles

role AreaRole {
  has $.length is rw;
  has $.width is rw;
  has $.radius is rw;

  method circA {
    return pi * ($.radius ** 2);
  }

  method rectA {
    return $.length * $.width;
  }
}

# Inherite the role in a class
class Shape does AreaRole {};
my $circle = Shape.new:
:radius(10);
say $circle.circA;

# ---- REGULAR EXPRESSIONS ----
# Regular Expressions (Regex) are used to
# 1. Search for a specific string in a large amount of data
# 2. Verify that a string has the proper format (Email, Phone #)
# 3. Find a string and replace it with another string
# 4. Format data into the proper form for importing for example

my $regStr1 = "Random words";

# You can use specific characters between
# m/stuff/
if $regStr1 ~~ m/word/ { put "Found word" };

# Search for whitespace with \s
if $regStr1 ~~ m/\s/ { put "Found space" };

# Backslashed Character Classes
# The uppercase same character is a match
# for anything except that match
# \n : Newline
# \h : Horizontal Whitespace
# \t : Tab
# \s : Whitespace
# \d : Digit
# \w : Letter, number or underscore
# . : Any single character
# + : 1 or More
# * : 0 or more
# ? : 0 or 1

# Search arrays
my @nA1 = (1, 2, 3, 4);
if @nA1 ~~ m/2/ { put "Found 2" };

# Match ranges of values and store regex
my $reg1 = rx/ <[ a .. d 1 2 3]>* /;

# Returns the 1st match
say "c e b 4" ~~ $reg1;
say @nA1 ~~ $reg1;

# Get all matches with m:global
my @matches = "cat and cat" ~~ m:global/cat/;
say @matches;
say +@matches;

my $regstr2 = "Cat rat mat fat pat dog";

# Any single character followed by at
my @matches2 = $regstr2 ~~ m:global/ \w+at /;
say @matches2;

# Only Cat, rat and mat (:i Ignores case)
my @matches3 = $regstr2 ~~ m:global:i/ <[crm]>+at /;
say @matches3;

# Anything except Cat, rat and mat
my @matches4 = $regstr2 ~~ m:global:i/ <-[crm]>+at /;
say @matches4;

# Match any character and periods
my $regstr3 = "F.B.I. I.R.S. CIA";
say $regstr3 ~~ m:global/ .\..\.. /;

# Match only 5 digit numbers
my $regstr4 = "12 12345 123";
say $regstr4 ~~ m:global/ \d ** 5 /;

# Match 3 through 5 digit numbers
say $regstr4 ~~ m:global/ \d ** 3..5 /;

# Check for phone number
my $regstr5 = "412-555-1212 88";
say $regstr5 ~~ m:global/ \d**3 \- \d**3 \- \d**4 /;

# Match 0 or 1
my $regstr6 = "cat cats";
say $regstr6 ~~ m:global/ <[cat]>+s? /;

# Match 0 or more
my $regstr7 = "doctor doctors doctor's";
say $regstr7 ~~ m:global/ <[doctr]>+<['s]>* /;

# Capture part of a match
my $regstr8 = "abcd";
say $regstr8 ~~ m:global/ (a)bc(d) /;

# Capture when 1 or another matches
my $regstr9 = "ab cb db";
say $regstr9 ~~ m:global/ [a||c] b /;

# Greedy & Lazy Matching
my $regstr10 = "catcatcat";
say $regstr10 ~~ m:global/ c .* t /; # Greedy
say $regstr10 ~~ m:global/ c .*? t /; # Not Greedy

# Whitespace isn't considered unless you use :s
my $regstr11 = "1 2 3";
say $regstr11 ~~ m:global/ 1  2  3 /;
say $regstr11 ~~ m:global/:s 1  2  3 /;

# ---- GRAMMARS ----
# Grammars are classes used to parse complex text

# Parse for numbers
grammar Number {
  # The first rule is called TOP
  # May contain a negative and 1 or more numbers
  # and maybe a .
  token TOP { \-? \d+ [\. \d+]? }
}

# Cycle through a list of numbers
for <1 23 -456 2.35> -> $num {
  say Number.parse($num);
}

# You can create multiple tokens each with
# their own rules
grammar Number2 {
  # Will get its sum match using tokens below
  token TOP {
    <sign>?<value>
  }
  token sign {
    '-'
  }
  token number {
    \d+
  }
  # Combination of all the above
  token value {
    | <number>
    | "." <number>
    | <number> "."
    | <number> "." <number>
  }
}

# Cycle through a list of numbers
for <1 23 -456 2.35> -> $num {
  say Number2.parse($num);
}

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# Install : https://www.rakudo.org/files/star/third-party

#`( multiline or inline

comment

)

# Most data in Perl 6 are objects

# ---- BASICS ----

# Output the string + newline

put 'Hello World';

# Receive user input and save to the variable $name

# my declares a variable

# The sigil $ comes before the variable name

# if you want the value to be changeable (mutable)

my $name = prompt "What's your name? ";

put "Hello $name";

# say normally provides the same output as put

# but it may abbreviate it

put 1 .. 10;

say 1 .. 10;

# print doesn't add a newline

print "No newline";

# ---- VARIABLES ----

# Variable names start with a letter or number

# and can contain underscores, hyphens and

# apostrophes

# You can declare an immutable (unchangeable)

# variable with \

my \pi = 3.1415;

# This would cause an error -> pi = 6;

# You can define types or not

# Common types : Bool, Int, Num (float),

# Real (Non-complex number), Str, Date

my Int $x;

# This would cause an error -> $x = "Dog";

my $y = 6;

$y = "Dog";

# The binding operator creates an alias to

# a variable

my $z := $y;

put $z;

# Booleans are True or False

# 0 is considered false everything else is true

my Bool $can-vote = True;

put $can-vote;

# You can use exponential notation

my $thousand = 1e3;

# Show types

put "10 : ", 10.^name;

put "10.5 : ", (10.5).^name;

put "\"10\" : ", "10".^name;

# Convert int as unicode to character

say '65'.chr;

# Convert numbers to strings

say "Type : ", (10.Str).^name;

# Convert strings to numbers

say "Type : ", (+"123").^name;

# Auto casting works

say "1 + 2 = ", "1" + 2;

# ---- MATH ----

# You can use common math functions

# This is another way to format output

# %d Integers, %f Floats, %s

say (5 + 4).fmt("5 + 4 = %d");

say (5 - 4).fmt("5 - 4 = %d");

say (5 * 4).fmt("5 * 4 = %d");

# Format float with 2 decimals

say (5 / 4).fmt("5 / 4 = %.2f");

say (5**4).fmt("5^4 = %d");

# Adding fractions

say (1/4 + 1/2).fmt("1/4 + 1/2 = %.2f");

# Generate random number between 0 and 20

say "Random : ", 20.rand.Int;

# Generate random value from range 5 to 20

say "Random Range : ", (5..20).rand.Int;

# You can expect 15 digits of precision

my $floatNum = 1.111111111111111111111111111111111111;

my $floatNum2 = 1.111111111111111111111111111111111111;

say "Big Float : ", $floatNum + $floatNum2;

# With math functions you can normally use

# funcName(), or attr.funcName

say "(-1).abs = ", (-1).abs;

say "1.exp = ", (1).exp; # e to the power of

say "sqrt(9) = ", sqrt(9);

say "log(2) = ", log(2);

say "log10(2) = ", log(100);

say "round(2.45) = ", round(2.45);

say "floor(2.45) = ", floor(2.45);

say "ceiling(2.45) = ", ceiling(2.45);

say "sin(0) = ", sin(0);

say "cos(0) = ", cos(0);

say "tan(0) = ", tan(0);

say "asin(0) = ", asin(0);

say "acos(0) = ", acos(0);

say "atan(0) = ", atan(0);

say "cotan(0) = ", cotan(0);

say "acotan(0) = ", acotan(0);

say "sinh(0) = ", sinh(0);

say "cosh(0) = ", cosh(0);

say "tanh(0) = ", tanh(0);

say "asinh(0) = ", asinh(0);

say "acosh(0) = ", acosh(0);

say "atanh(0) = ", atanh(0);

say "atan2(100) = ", atan2(100);

# ---- CONDITIONALS ----

# Conditional Operators > < >= <= == !-

# Logical Operators : && and, || or, ! not

my $age = 12;

if $age >= 5 && $age <= 6 {

put "Go to Kindergarten";

# Shortcut chained comparison

} elsif 7 <= $age <= 13 {

put "Go to Middle School";

} elsif $age >= 14 && $age <= 18 {

put "Go to High School";

} else {

put "Stay Home";

}

# Execute only if true

put 'Old enough for school' if $age >= 5;

# Execute if condition is false

my $k = 0;

unless $k == 5 {

put $k;

}

# Ternary operator : If true use 1st

# otherwise use 2nd as output

put 'Can vote : ', $age >= 18 ?? 'True' !! 'False';

# ---- STRINGS -----

# Create a string

my $str1 = "Hello";

# You can use variables in output with ""

say "$str1";

# Use quotes by escaping

# \n, \t, \r, \b, \a, \f

say "I like \"quotes\"";

# Number of characters

say "Num : ", $str1.chars;

# Does it have a value

say "Has Value : ", ?$str1;

# To use protected characters surround

# the output with Q and delimiters

say Q/$str1 is ok here/;

# You can also use single quotes

say '$str1 is ok here';

# Concatenate STRINGS

say "one " ~ "string";

# Join also concatenates and puts the first

# string between the next 2 or more

my $str2 = join " ", "a", "long", "string";

say $str2;

# Multiline strings

my $str3 = q :heredoc/END/;

I go

for

many

lines

END

say $str3;

# Does a string contain a string

say "Long? ", $str2.contains("long");

# Add fc to make it case insensitive

say "Long? ", $str2.fc.contains("long");

# Get index where you have a match

my $sI = $str2.index("long");

# Get a substring starting with index 0

# You can often use : instead of ()s with functions

say $str2.substr: $sI, 5;

# Trim whitespace

# Also .trim-leading & .trim-trailing

say "Bye whitespace : ", " abc ".trim;

# Lowercase, uppercase, titlecase

say "ABC".lc;

say "abc".uc;

say "abc".tclc;

# Are strings equal

say "Dog".lc eq "dog";

# Greater than is based on alphabetical

# order and uppercase > Lowercase

# Also there is lt

say "GT : ", "abc" gt "d";

# Remove last character

say "abc".chop;

# Remove a newline

say "abc\n".chomp;

# Use variables without spaces

say "{$str1}, Derek";

# Code in strings

say "5 * 4 = {5*4}";

# Use interpolation only between braces

say q :c "\n 1 + 2 = {1+2}";

# Get character by Code

say "\x[40]";

# Duplicate strings

say $str1 x 5;

# Split based on delimiter

say split(', ', "a, b, c");

# Split using Regex

say split(/<[;,]>/, "a,b;c");

# Split using another Regex

say "a b c".split: / \s /;

# Replace matches

my $str5 = "Derek is terrible";

put $str5.subst: /terrible/, 'Awesome';

# ---- LOOPING ----

# Execute as long as a condition is true

loop (my $i = 1; $i < 20; $i++){

# Print only even numbers

if $i mod 2 == 0 {

put $i;

# Like continue in other languages

next;

}

if $i >= 10 {

# Jumps out of loop like break

last;

}

# Print 0 .. 4

loop {

# Marking this as state sets the value

# only one time

state $j = 0;

# Print and then add 1

put $j++;

# Leave loop when true

last if $j == 5;

}

# While loop

my $i1 = 0;

while $i1 < 5 {

put $i1++;

}

# Repeat while executes once and then checks

# the condition

repeat while $i1 < 5 {

put $i1++;

}

loop {

state $k = 0;

put $k++;

last if $k >= 5;

# Phasers run at the beginning and

# end of a loop

FIRST {say "Starting"}

LAST {say "Ending"}

}

# ---- BLOCKS ----

# You can store blocks of Code

# $_ represents a passed parameter

my $sayHello := { say "Hello $_"};

$sayHello("Derek");

# Use multiple parameters

my $addNums := {$^a + $^b};

say $addNums(1,2);

# You can use Thunks (*) to create closures

# or Whatever codes

my $plus2 = * + 2;

say $plus2(5);

# Subsets can be used to create data types

# that only hold evens for example

subset EvenInt of Int where { $^a mod 2 == 0 };

my EvenInt $eVal = 4;

say $eVal;

# ---- LISTS & ARRAYS ----

# An immutable series of values

my $l1 = List.new: 1, 2, 3;

# Using @ instead of $ provides for shortcuts

# and you create an array thats values can

# be changed

my @l2 = (1, 2, 3);

# Get number of values

say $l1.elems;

say @l2.elems;

# Create a list with values separated by

# spaces

my @l3 = <Mark Sally Paul Sam>;

say @l3.elems;

# Get a value by index

put @l3[0];

# Get a range of values

put @l3[0, 1];

# Change a value

@l3[2] = "Pam";

# Shift off the 1st array element

put @l3.shift;

# Shift a new value on the front

@l3.unshift: <Peter Pat>;

# Pop off the last

put @l3.pop;

# Push items onto the end

@l3.push: <Zack>;

# Splice off values by index

@l3.splice: 0, 2;

# Search for a match

say "Pam : ", @l3.grep("Pam");

# Filter a list

say "Evens ", (1..10).grep: {$_ %% 2};

# Cycle through list with for

for @l3 {

# $_ is the topic variable

say "$_";

}

# Get multiple values at once

for @l3 -> $x, $y {

say "$x $y";

}

# Get key and index

for @l3.kv -> $index, $item {

say "index $index : item $item";

}

# Sort lists

say sort @l3;

# Create a list of lists

my $l4 = ( <1 2>, <3 4> );

say "00 : ", $l4[0][0];

# Combine 2 lists into one

say zip( <a b>, <1 2>);

# Declare 2 variables at once

my ($val2, $val3) = <a b>;

# Store variables in lists without commas

my $l5 = <<$val2 $val3>>;

put $l5;

# Output with delimiters

put $l5.join(', ');

# Turn a string into an array

# .comb creates a list of characters

my $str4 = "a b c d";

my $l6 = $str4.words;

put $l6;

# Reverse list

put $l6.reverse;

# Maps allow us to transform each element of

# an array (Multiply every value by 2)

my @l7 = 1, 2, 3;

my @map1 = map { $_ * 2 }, @l7;

say @map1;

# Add 2 lists with a hyperoperator

# You can use -, *, /

my @l8 = 4, 5, 6;

say @l7 <<+>> @l8;

# ---- RANGES ----

# You can create ranges of values as

# long as they are in order 1,2,3 a,b,c

# Ranges are not lists

my $r1 = 1 .. 5; # Not 5 .. 1

# Turn a range into a list

my $rl1 = $r1.List;

# Exclude left or right most value

my $r2 = 1 ^.. 5;

my $r3 = 1 ..^ 5;

# ---- SEQUENCES ----

# Sequences are lists that defer the

# creation of values and then doesn't

# store them

my $seq1 := 1 ... 10;

# Sequences can count down

my $seq2 := 10 ... 1;

# They can be created using an algorithm

# Fibonacci series : 1,1,2,3,5,8,13,

my $fib := 0, 1, -> $a, $b { $a + $b } ... *; 1;

put $fib[^10].join(', ');

# Check for lazy lists

put "Lazy : ", $fib.is-lazy;

# ---- SETS ----

# Sets are lists with no duplicates

my $mySet = set(1,2,3,3);

say $mySet.elems;

# ---- MAPS ----

# Maps are immutable lists of ky value pairs

my $japFam = Map.new:

'Dad', 'Otousan',

'Mom', 'OKaasan',

'Son', 'Oniisan',

'Daughter', 'Oneesan';

# Get value with key

say $japFam<Dad>;

# Check if exists

say $japFam{'Mom'}:exists;

# Get keys and values

for $japFam.kv -> $key, $item {

put "$key => $item";

}

# ---- HASHES ----

# Mutable maps

my $japColor = Hash.new:

'Blue', 'Aoo',

'Red', 'Aka',

'Green', 'Midori';

# Change a value

$japColor<Blue> = 'Ao';

# Delete kv

$japColor<Blue>:delete;

# Add kv

$japColor<White> = "Shiro";

# Get KVs

for $japColor.kv -> $key, $item {

put "$key => $item";

}

# ---- SUBROUTINES / FUNCTIONS ----

# Subroutines use return to return values

# sub name (arguments with or without types)

# You can give default values if you want

sub addNums2 ($a = 1, $b = 1){

return $a + $b;

}

say "1 + 3 = ", addNums2(1,3);

# Arguments can be optional

sub giveMe ($arg?){

return $arg;

}

say giveMe();

say giveMe(1);

# Store function in a variable

my &sub1 = &addNums2;

say &sub1(1,3);

# Use a slurpy parameter to accept an

# unknown number of arguments

sub addNums3(*@nums){

state $sum = 0;

for @nums -> $num {

$sum = $sum + $num;

}

return $sum;

}

say "Sum : ", addNums3 1, 2, 3, 4 ;

# Return multiple values

sub nextTwo($a){

return $a + 1, $a + 2;

}

say nextTwo(1);

# You can pass a function as a value

# for example to square values in a list

sub square($a){ $a * $a };

my @squaredList = map &square, 1..5;

say join ', ', @squaredList;

# Recursion is when a function calls itself

# Calculate a factorial

sub factorial($a){

if ($a == 1) {

return 1;

} else {

return $a * factorial($a - 1);

}

say factorial(4);

# 1st : result = 4 * factorial(3) = 4 * 6 = 24

# 2nd : result = 3 * factorial(2) = 3 * 2 = 6

# 3rd : result = 2 * factorial(1) = 2 * 1 = 2

# ---- EXCEPTION HANDLING ----

# We can set up our code to catch errors

# Surround problematic code with try

try {

# my $ans = (10 %% 0);

# Throw your own exception

die 'Bad Stuff';

# List exceptions to catch here

CATCH {

# $_ stores the error message

when X::Numeric::DivideByZero {

say "Error : $_";

}

default {

say "Default : $_";

}

# ---- FILE I/O ----

# Create a file for writing

my $f1 = open "mydata", :w;

# Write text to it

$f1.print("file stuff\n");

my $myName = "Derek";

$f1.printf("My name is %s\n", $myName);

# Close file

$f1.close;

# spurt opens, writes and closes the file

# Remove :append to overwrite

spurt "mydata", "spurts stuff\n", :append;

# Read from a file

my $f2 = open "mydata", :r;

my $myData = $f2.slurp;

say $myData;

$f2.close;

# ---- FILE MANIPULATION ----

# Check if file exists

if "mydata".IO.e {

say "Exists";

# When was file edited

say "mydata".IO.modified.DateTime;

# Read

say "mydata".IO.accessed.DateTime;

# Size

say "mydata".IO.s;

}

# Rename file

rename "mydata", "mydata2";

# Copy file

copy "mydata2", "mydataBU";

# Make a directory

mkdir "Perl Stuff";

# Does directory exist

say "Perl Stuff".IO.d;

# Get directory listing

say dir;

# Remove empty directory

rmdir "Perl Stuff" or die "$!";

# You can run any shell commands

shell('ls -l');

# Store the result of the command

my $shellOP = Q:x{ls -l};

# ---- GRABBING DATA & MODULES ----

# zef is used to install modules that

# provide premade functions and such

# Modules : modules.perl6.org

# Install Popular : zef install Task::Popular

# Install HTTP::UserAgent with

# zef install HTTP::UserAgent

# Used to fetch data

use HTTP::UserAgent;

my $uA = HTTP::UserAgent.new;

# How long to wait

$uA.timeout = 10;

# The URL

my $url = "http://www.gutenberg.org/cache/epub/58670/pg58670.txt";

# See if you can get the data

my $response = $uA.get($url);

my $dW;

# Get data or fail

if $response.is-success {

$dW = $response.content;

} else {

die $response.status-line;

}

# Output 10 lines

for $dW.lines(10) -> $text {

say $text;

}

# ---- CLASSES ----

# Classes simulate real world objects by

# defining attributes and capabilities (methods)

class Animal {

# Create a private attribute with $!

has $!name = '';

# Public with $. (Make read/writable)

# Define data type or don't

has Real $.height is rw = 0.0;

has $.weight is rw = 0.0;

# Constructor that is called when an

# object is created

# The ! after name requires its value

method BUILD(:$name!, :$height, :$weight) {

$!name = $name;

# Handle if values aren't passed

if $height {

$.height = $height;

} else {

$.height = 0;

}

if $weight {

$.weight = $weight;

} else {

$.weight = 0;

}

# Provides access to the name (Getter)

method name { $!name; }

# You could make name mutable

# method name is rw { $!name; }

# Self provides a way to refer to an object

method info {

return "{self.name} is {self.height}cms tall and

{self.weight}kgs";

}

# This is an abstract method subclasses

# will implement

method makeSound { !!! }

}

# Create an Animal

my $spot = Animal.new:

:name('Spot')

:height(63)

:weight(40);

# Get the name value

say $spot.name;

# This would throw an error without is rw

# $spot.name = 'dog';

$spot.height = 63.5;

$spot.weight = 35.5;

say $spot.info;

# ---- INHERITANCE ----

# Inheriate methods and attributes from Animal

class Dog is Animal {

has $.sound is rw = "Woof";

# Overwrite method

method info {

# callsame executes the superclass function

# with the same name

my $origMsg = callsame;

# Combine the strings with ~

return $origMsg ~ " and says {self.sound}";

}

# Implement the abstract method

method makeSound {

return "{self.name} says {self.sound}";

}

my $doug = Dog.new:

:name('Doug')

:height(63);

say $doug.name;

say $doug.weight;

say $doug.info;

# ---- ROLES ----

# You can add capabilities to objects

# with roles

role AreaRole {

has $.length is rw;

has $.width is rw;

has $.radius is rw;

method circA {

return pi * ($.radius ** 2);

}

method rectA {

return $.length * $.width;

}

# Inherite the role in a class

class Shape does AreaRole {};

my $circle = Shape.new:

:radius(10);

say $circle.circA;

# ---- REGULAR EXPRESSIONS ----

# Regular Expressions (Regex) are used to

# 1. Search for a specific string in a large amount of data

# 2. Verify that a string has the proper format (Email, Phone #)

# 3. Find a string and replace it with another string

# 4. Format data into the proper form for importing for example

my $regStr1 = "Random words";

# You can use specific characters between

# m/stuff/

if $regStr1 ~~ m/word/ { put "Found word" };

# Search for whitespace with \s

if $regStr1 ~~ m/\s/ { put "Found space" };

# Backslashed Character Classes

# The uppercase same character is a match

# for anything except that match

# \n : Newline

# \h : Horizontal Whitespace

# \t : Tab

# \s : Whitespace

# \d : Digit

# \w : Letter, number or underscore

# . : Any single character

# + : 1 or More

# * : 0 or more

# ? : 0 or 1

# Search arrays

my @nA1 = (1, 2, 3, 4);

if @nA1 ~~ m/2/ { put "Found 2" };

# Match ranges of values and store regex

my $reg1 = rx/ <[ a .. d 1 2 3]>* /;

# Returns the 1st match

say "c e b 4" ~~ $reg1;

say @nA1 ~~ $reg1;

# Get all matches with m:global

my @matches = "cat and cat" ~~ m:global/cat/;

say @matches;

say +@matches;

my $regstr2 = "Cat rat mat fat pat dog";

# Any single character followed by at

my @matches2 = $regstr2 ~~ m:global/ \w+at /;

say @matches2;

# Only Cat, rat and mat (:i Ignores case)

my @matches3 = $regstr2 ~~ m:global:i/ <[crm]>+at /;

say @matches3;

# Anything except Cat, rat and mat

my @matches4 = $regstr2 ~~ m:global:i/ <-[crm]>+at /;

say @matches4;

# Match any character and periods

my $regstr3 = "F.B.I. I.R.S. CIA";

say $regstr3 ~~ m:global/ .\..\.. /;

# Match only 5 digit numbers

my $regstr4 = "12 12345 123";

say $regstr4 ~~ m:global/ \d ** 5 /;

# Match 3 through 5 digit numbers

say $regstr4 ~~ m:global/ \d ** 3..5 /;

# Check for phone number

my $regstr5 = "412-555-1212 88";

say $regstr5 ~~ m:global/ \d**3 \- \d**3 \- \d**4 /;

# Match 0 or 1

my $regstr6 = "cat cats";

say $regstr6 ~~ m:global/ <[cat]>+s? /;

# Match 0 or more

my $regstr7 = "doctor doctors doctor's";

say $regstr7 ~~ m:global/ <[doctr]>+<['s]>* /;

# Capture part of a match

my $regstr8 = "abcd";

say $regstr8 ~~ m:global/ (a)bc(d) /;

# Capture when 1 or another matches

my $regstr9 = "ab cb db";

say $regstr9 ~~ m:global/ [a||c] b /;

# Greedy & Lazy Matching

my $regstr10 = "catcatcat";

say $regstr10 ~~ m:global/ c .* t /; # Greedy

say $regstr10 ~~ m:global/ c .*? t /; # Not Greedy

# Whitespace isn't considered unless you use :s

my $regstr11 = "1 2 3";

say $regstr11 ~~ m:global/ 1 2 3 /;

say $regstr11 ~~ m:global/:s 1 2 3 /;

# ---- GRAMMARS ----

# Grammars are classes used to parse complex text

# Parse for numbers

grammar Number {

# The first rule is called TOP

# May contain a negative and 1 or more numbers

# and maybe a .

token TOP { \-? \d+ [\. \d+]? }

}

# Cycle through a list of numbers

for <1 23 -456 2.35> -> $num {

say Number.parse($num);

}

# You can create multiple tokens each with

# their own rules

grammar Number2 {

# Will get its sum match using tokens below

token TOP {

}

token sign {

'-'

}

token number {

\d+

}

# Combination of all the above

token value {

| <number>

| "." <number>

| <number> "."

| <number> "." <number>

}

# Cycle through a list of numbers

for <1 23 -456 2.35> -> $num {

say Number2.parse($num);

}

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Perl 6 Tutorial

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