This document provides an introduction to the Elixir programming language. It discusses what Elixir is, how to get started with installation and configuration of Elixir and Erlang, basic and compound data types in Elixir, functions and modules, and higher-order functions and comprehensions. Key topics covered include installing Elixir using ASDF, basic data types like integers, floats, atoms, and more, functions and anonymous functions, modules, and Enum functions like map, reduce, and comprehensions.

1. Pre-bootcamp
introduction to Elixir
Paweł Dawczak

2. # 1. Introduction - what is Elixir, how to start?
# 2. Basic and compound data types
# 3. Functions and modules
# 4. Let’s talk about `=`
# 5. Let’s have some fun!
# 6. Let’s talk about `mix`
# 7. Let’s talk about dependencies
# 8. Suggestions where to find more information
# 9. QA

3. # What is Elixir?

8. # Background

11. JVM

12. BEAM

13. Erlang/OTP
O
T
P

14. Erlang/OTP
O - Open
T - Telecom
P - Platform

16. José Valim

18. -module(my_module).
-export([hello/1]).
hello(Str) ->
my_helper(Str).
my_helper(Str) ->
string:reverse(string:uppercase(Str)).

19. -module(my_module).
-export([hello/1]).
hello(Str) ->
my_helper(Str).
my_helper(Str) ->
string:reverse(string:uppercase(Str)).
defmodule MyModule do
def hello(str) do
my_helper(str)
end
defp my_helper(str) do
str
|> String.upcase()
|> String.reverse()
end
end

20. # Where do I start?

22. # Install erlang
$ asdf plugin-add erlang
$ asdf list-all erlang # will list all the available versions
$ asdf install erlang 20.3.7
$ asdf global erlang 20.3.7

23. # Install erlang
$ asdf plugin-add erlang
$ asdf list-all erlang # will list all the available versions
$ asdf install erlang 20.3.7
$ asdf global erlang 20.3.7
# Install Elixir
$ asdf plugin-add elixir
$ asdf list-all elixir
$ asdf install elixir 1.6.5
$ asdf global elixir 1.6.5

24. # Install erlang
$ asdf plugin-add erlang
$ asdf list-all erlang # will list all the available versions
$ asdf install erlang 20.3.7
$ asdf global erlang 20.3.7
# Install Elixir
$ asdf plugin-add elixir
$ asdf list-all elixir
$ asdf install elixir 1.6.5
$ asdf global elixir 1.6.5
# [Optional] Install Node

25. # Basic data types

26. nil # => nil
true # => true
:test # => :test

27. nil # => nil
true # => true
:test # => :test
1 # => 1
1.2 # => 1.2
"Testing" # => "Testing"
'Testing' # => 'Testing'

28. nil # => nil
true # => true
:test # => :test
1 # => 1
1.2 # => 1.2
"Testing" # => "Testing"
'Testing' # => 'Testing'
is_binary("Testing") # => true
is_binary('Testing') # => false
is_list("Testing") # => false
is_list('Testing') # => true

29. nil # => nil
true # => true
:test # => :test
1 # => 1
1.2 # => 1.2
"Testing" # => "Testing"
'Testing' # => 'Testing'
is_binary("Testing") # => true
is_binary('Testing') # => false
is_list("Testing") # => false
is_list('Testing') # => true
pid(0, 13, 0) # => #PID<0.13.0>

30. nil # => nil
true # => true
:test # => :test
1 # => 1
1.2 # => 1.2
"Testing" # => "Testing"
'Testing' # => 'Testing'
is_binary("Testing") # => true
is_binary('Testing') # => false
is_list("Testing") # => false
is_list('Testing') # => true
pid(0, 13, 0) # => #PID<0.13.0>
make_ref() # => #Reference<0.1816712181.2865233921.217076>
# The reference is unique among connected nodes.

31. # Compound data types

32. # Lists
[1, 2, 3] # => [1, 2, 3]

33. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}

34. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"

35. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]

36. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]
opts[:per_page] # => 3

37. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]
opts[:per_page] # => 3
Keyword.get_values(opts, :per_page) # => [3, 5]

38. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]
opts[:per_page] # => 3
Keyword.get_values(opts, :per_page) # => [3, 5]
# Structs

39. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]
opts[:per_page] # => 3
Keyword.get_values(opts, :per_page) # => [3, 5]
# Structs
defmodule User do
end

40. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]
opts[:per_page] # => 3
Keyword.get_values(opts, :per_page) # => [3, 5]
# Structs
defmodule User do
defstruct [:first_name, :last_name, username: "Guest"]
end

41. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]
opts[:per_page] # => 3
Keyword.get_values(opts, :per_page) # => [3, 5]
# Structs
defmodule User do
defstruct [:first_name, :last_name, username: "Guest"]
end
%User{first_name: "Pawel", last_name: "Dawczak"}

42. # Lists
[1, 2, 3] # => [1, 2, 3]
# Tuples
{:ok, "Test"} # => {:ok, "Test"}
# Maps
map = %{first_name: "Pawel", last_name: "Dawczak"} # => %{first_name: "Pawel", last_name: "Dawczak"}
map[:first_name] # => "Pawel"
# Keyword Lists
opts = [per_page: 3, current_page: 1, per_page: 5] # => [per_page: 3, current_page: 1, per_page: 5]
opts[:per_page] # => 3
Keyword.get_values(opts, :per_page) # => [3, 5]
# Structs
defmodule User do
defstruct [:first_name, :last_name, username: "Guest"]
end
%User{first_name: "Pawel", last_name: "Dawczak"}
# => User{first_name: "Pawel", last_name: "Dawczak", username: "Guest"}

43. # Functions and modules

44. # Functions
inc = fn x -> x + 1 end
inc.(3) # => 4

45. # Functions
inc = fn x -> x + 1 end
inc.(3) # => 4
# Capture operator
dec = &(&1 - 1)
dec.(3) # => 2

46. # Functions
inc = fn x -> x + 1 end
inc.(3) # => 4
# Capture operator
dec = &(&1 - 1)
dec.(3) # => 2
# Modules
defmodule MyModule do
end

47. # Functions
inc = fn x -> x + 1 end
inc.(3) # => 4
# Capture operator
dec = &(&1 - 1)
dec.(3) # => 2
# Modules
defmodule MyModule do
def square(x) do
x * 2
end
end
MyModule.square(4) # => 8

48. # Functions
inc = fn x -> x + 1 end
inc.(3) # => 4
# Capture operator
dec = &(&1 - 1)
dec.(3) # => 2
# Modules
defmodule MyModule do
def square(x) do
x * 2
end
def multi(x, y), do: x * y
end
MyModule.square(4) # => 8
MyModule.multi(3, 4) # => 12

49. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]

50. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions

51. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]

52. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]

53. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string/1) # => ["1", "2", "3"]

54. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string/1) # => ["1", "2", "3"]
Enum.reduce(1..3, 0, fn num, acc -> num + acc end) # => 6

55. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string/1) # => ["1", "2", "3"]
Enum.reduce(1..3, 0, fn num, acc -> num + acc end) # => 6
Enum.reduce(1..3, 0, &(&1 + &2)) # => 6

56. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string/1) # => ["1", "2", "3"]
Enum.reduce(1..3, 0, fn num, acc -> num + acc end) # => 6
Enum.reduce(1..3, 0, &(&1 + &2)) # => 6
Enum.reduce(1..3, 0, &+/2) # => 6

57. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string/1) # => ["1", "2", "3"]
Enum.reduce(1..3, 0, fn num, acc -> num + acc end) # => 6
Enum.reduce(1..3, 0, &(&1 + &2)) # => 6
Enum.reduce(1..3, 0, &+/2) # => 6
pass = "MySecretPass123"

58. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string/1) # => ["1", "2", "3"]
Enum.reduce(1..3, 0, fn num, acc -> num + acc end) # => 6
Enum.reduce(1..3, 0, &(&1 + &2)) # => 6
Enum.reduce(1..3, 0, &+/2) # => 6
pass = "MySecretPass123"
Enum.map([3, 8, 14], fn x -> String.at(pass, x) end) # => ["e", "P", "3"]

59. # Comprehensions
for x <- (1..5),
y <- [:blue, :red],
rem(x, 2) == 0,
do: "#{x * x}-#{y}" # => ["4-blue", "4-red", "16-blue", "16-red"]
# Higher-order functions
Enum.map([1, 2, 3], fn num -> to_string(num) end) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string(&1)) # => ["1", "2", "3"]
Enum.map([1, 2, 3], &to_string/1) # => ["1", "2", "3"]
Enum.reduce(1..3, 0, fn num, acc -> num + acc end) # => 6
Enum.reduce(1..3, 0, &(&1 + &2)) # => 6
Enum.reduce(1..3, 0, &+/2) # => 6
pass = "MySecretPass123"
Enum.map([3, 8, 14], fn x -> String.at(pass, x) end) # => ["e", "P", "3"]
Enum.map([3, 8, 14], &String.at(pass, &1)) # => ["e", "P", "3"]

60. # Let’s talk about `=`

61. x = 1
1 = x
2 = x
** (MatchError) no match of right hand side value: 1
^x = 1 # ^ - pin operator
^x = 2
list = [20, 21, 22]
[a, b, c] = list
a # => 20
b # => 21
[a, ^x, c] = list
** (MatchError) no match of right hand side value: [20, 21, 22]
hd(list) # => 20
tl(list) # => [21, 22]
[head | tail] = list
head # => 20
tail # => [21, 22]
[a2, 21 | tail] = list
a2 # => 20
tail # => [22]

62. map = %{a: "Foo", b: "Bar"}

63. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"

64. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map

65. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}

66. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}
defmodule Employee do
end

67. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}
defmodule Employee do
defstruct [:name, :lang]
end

68. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}
defmodule Employee do
defstruct [:name, :lang]
end
p = %Employee{name: "Pawel", lang: "Elixir"}

69. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}
defmodule Employee do
defstruct [:name, :lang]
end
p = %Employee{name: "Pawel", lang: "Elixir"}
%{name: name} = p
name # => "Pawel"

70. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}
defmodule Employee do
defstruct [:name, :lang]
end
p = %Employee{name: "Pawel", lang: "Elixir"}
%{name: name} = p
name # => "Pawel"
%Employee{name: name} = p
name # => "Pawel"

71. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}
defmodule Employee do
defstruct [:name, :lang]
end
p = %Employee{name: "Pawel", lang: "Elixir"}
%{name: name} = p
name # => "Pawel"
%Employee{name: name} = p
name # => "Pawel"
lang = "Elixir"

72. map = %{a: "Foo", b: "Bar"}
%{a: a} = map
a # => "Foo"
%{a: "Baz", b: b} = map
** (MatchError) no match of right hand side value: %{a: "Foo", b: "Bar"}
defmodule Employee do
defstruct [:name, :lang]
end
p = %Employee{name: "Pawel", lang: "Elixir"}
%{name: name} = p
name # => "Pawel"
%Employee{name: name} = p
name # => "Pawel"
lang = "Elixir"
%Employee{name: name, lang: ^lang} = p
name # => "Pawel"

73. File.read("./nice_file")

74. File.read("./nice_file") # => {:ok, "Hello World! Nice to see you all!n"}

75. File.read("./nice_file") # => {:ok, "Hello World! Nice to see you all!n"}
File.read("./non_existing_one") # => {:error, :enoent}

76. File.read("./nice_file") # => {:ok, "Hello World! Nice to see you all!n"}
File.read("./non_existing_one") # => {:error, :enoent}
File.read!("./non_existing_one")
** (File.Error) could not read file "./non_existing_one": no such file or directory

77. File.read("./nice_file") # => {:ok, "Hello World! Nice to see you all!n"}
File.read("./non_existing_one") # => {:error, :enoent}
File.read!("./non_existing_one")
** (File.Error) could not read file "./non_existing_one": no such file or directory
HTTPoison.get("https://google.com")

78. File.read("./nice_file") # => {:ok, "Hello World! Nice to see you all!n"}
File.read("./non_existing_one") # => {:error, :enoent}
File.read!("./non_existing_one")
** (File.Error) could not read file "./non_existing_one": no such file or directory
HTTPoison.get("https://google.com")
{:ok,
%HTTPoison.Response{
body: "...",
headers: [
{"Location", "https://www.google.com/"},
{"Content-Type", "text/html; charset=UTF-8"},
{"Cache-Control", "public, max-age=2592000"},
{"Server", "gws"},
{"Content-Length", "220"},
{"X-Frame-Options", "SAMEORIGIN"},
],
request_url: "https://google.com",
status_code: 301
}}

79. String.reverse(String.upcase(format.(String.replace("My Content - 1", ~r/W/, "_"))))

80. String.reverse(String.upcase(format.(String.replace("My Content - 1", ~r/W/, "_"))))
# Pipe operator
String.replace("My Content - 1", ~r/W/, "_")
|> format.()
|> String.upcase()
|> String.reverse()

81. String.reverse(String.upcase(format.(String.replace("My Content - 1", ~r/W/, "_"))))
# Pipe operator
String.replace("My Content - 1", ~r/W/, "_")
|> format.()
|> String.upcase()
|> String.reverse()
# Pipe operator in action

82. String.reverse(String.upcase(format.(String.replace("My Content - 1", ~r/W/, "_"))))
# Pipe operator
String.replace("My Content - 1", ~r/W/, "_")
|> format.()
|> String.upcase()
|> String.reverse()
# Pipe operator in action
process = fn
{:ok, %{body: body}} ->
# parse the body, etc…
{:error, error_message} ->
Logger.error("Request failed due to: #{error_message}")
end

83. String.reverse(String.upcase(format.(String.replace("My Content - 1", ~r/W/, "_"))))
# Pipe operator
String.replace("My Content - 1", ~r/W/, "_")
|> format.()
|> String.upcase()
|> String.reverse()
# Pipe operator in action
process = fn
{:ok, %{body: body}} ->
# parse the body, etc…
{:error, error_message} ->
Logger.error("Request failed due to: #{error_message}")
end
"https://google.com"
|> HTTPoison.get()
|> process.()

85. # Let the fun begin!

86. # 1. Fibonacci!

88. # 1. Fibonacci!
defmodule Fib do
def of(0), do: 1
def of(1), do: 1
def of(n) when n > 1, do: of(n-1) + of(n-2)
end
Fib.of(5)
Fib.of(-6)

90. # 2. map

91. # 2. map
M.map([], fn x -> x * x end) # => []
M.map([1, 2, 3], fn x -> x * x end) # => [1, 4, 9]

92. # 2. map
defmodule M do
def map(list, fun), do: do_map(list, fun, [])
defp do_map([], _fun, acc), do: Enum.reverse(acc)
defp do_map([head | tail], fun, acc) do
result = fun.(head)
do_map(tail, fun, [result | acc])
end
end
M.map([], fn x -> x * x end) # => []
M.map([1, 2, 3], fn x -> x * x end) # => [1, 4, 9]

94. # 3. dedup

95. # 3. dedup
[1, 1, 1, 2, 3, 3]

96. # 3. dedup
[1, 1, 1, 2, 3, 3] => [{3, 1}, 2, {2, 3}]

97. # 3. dedup
3
1
1
1
list acc

98. # 3. dedup
1
1
1 3
list acc

99. # 3. dedup
1
{2, 1}
3
list acc

100. # 3. dedup
{3, 1}
3
list acc

101. # 3. dedup
list acc
3
{3, 1}
reversed

102. # 3. dedup
defmodule D do
end
D.dedup([1, 2, 3, 4]) # => [1, 2, 3, 4]
D.dedup([1, 1, 1, 2, 3, 3]) # => [{3, 1}, 2, {2, 3}]

103. # 3. dedup
defmodule D do
def dedup(list), do: do_dedup(list, [])
end
D.dedup([1, 2, 3, 4]) # => [1, 2, 3, 4]
D.dedup([1, 1, 1, 2, 3, 3]) # => [{3, 1}, 2, {2, 3}]

104. # 3. dedup
defmodule D do
def dedup(list), do: do_dedup(list, [])
defp do_dedup([], acc), do: Enum.reverse(acc)
end
D.dedup([1, 2, 3, 4]) # => [1, 2, 3, 4]
D.dedup([1, 1, 1, 2, 3, 3]) # => [{3, 1}, 2, {2, 3}]

105. # 3. dedup
defmodule D do
def dedup(list), do: do_dedup(list, [])
defp do_dedup([], acc), do: Enum.reverse(acc)
defp do_dedup([num, num | tail], acc) do
do_dedup(tail, [{2, num} | acc])
end
end
D.dedup([1, 2, 3, 4]) # => [1, 2, 3, 4]
D.dedup([1, 1, 1, 2, 3, 3]) # => [{3, 1}, 2, {2, 3}]

106. # 3. dedup
defmodule D do
def dedup(list), do: do_dedup(list, [])
defp do_dedup([], acc), do: Enum.reverse(acc)
defp do_dedup([num | tail], [{cnt, num} | acc_tail]) do
do_dedup(tail, [{cnt + 1, num} | acc_tail])
end
defp do_dedup([num, num | tail], acc) do
do_dedup(tail, [{2, num} | acc])
end
end
D.dedup([1, 2, 3, 4]) # => [1, 2, 3, 4]
D.dedup([1, 1, 1, 2, 3, 3]) # => [{3, 1}, 2, {2, 3}]

107. # 3. dedup
defmodule D do
def dedup(list), do: do_dedup(list, [])
defp do_dedup([], acc), do: Enum.reverse(acc)
defp do_dedup([num | tail], [{cnt, num} | acc_tail]) do
do_dedup(tail, [{cnt + 1, num} | acc_tail])
end
defp do_dedup([num, num | tail], acc) do
do_dedup(tail, [{2, num} | acc])
end
defp do_dedup([head | tail], acc), do: do_dedup(tail, [head | acc])
end
D.dedup([1, 2, 3, 4]) # => [1, 2, 3, 4]
D.dedup([1, 1, 1, 2, 3, 3]) # => [{3, 1}, 2, {2, 3}]

108. # 3. dedup
defmodule D do
def dedup(list), do: do_dedup(list, [])
defp do_dedup([], acc), do: Enum.reverse(acc)
defp do_dedup([num | tail], [{cnt, num} | acc_tail]) do
do_dedup(tail, [{cnt + 1, num} | acc_tail])
end
defp do_dedup([num, num | tail], acc) do
do_dedup(tail, [{2, num} | acc])
end
defp do_dedup([head | tail], acc), do: do_dedup(tail, [head | acc])
end
D.dedup([1, 2, 3, 4]) # => [1, 2, 3, 4]
D.dedup([1, 1, 1, 2, 3, 3]) # => [{3, 1}, 2, {2, 3}]

110. # 4. 5 most common words - eager approach

111. # 4. 5 most common words - eager approach
defmodule Eager do
def answer do
File.read!("moby.txt")
|> String.split("n")
|> Enum.map(%String.trim/1)
|> Enum.filter(&(&1 != ""))
|> Enum.flat_map(&String.split/1)
|> Enum.filter(&(String.length(&1) > 3))
|> Enum.reduce(%{}, fn word, words ->
Map.update(words, word, 1, fn curr -> curr + 1 end)
end)
|> Enum.sort_by(fn {_word, count} -> count end, &>=/2)
|> Enum.take(5)
end
end
Eager.answer()
# => [{"that", 2692}, {"with", 1695}, {"this", 1169}, {"from", 1072}, {"have", 752}]

112. # 5. 5 most common words - lazy approach
defmodule Lazy do
def answer do
File.stream!("moby.txt")
|> Stream.map(&String.trim/1)
|> Stream.filter(&(&1 != ""))
|> Stream.flat_map(&String.split/1)
|> Stream.filter(&(String.length(&1) > 3))
|> Enum.reduce(%{}, fn word, words ->
Map.update(words, word, 1, fn curr -> curr + 1 end)
end)
|> Enum.sort_by(fn {_word, count} -> count end, &>=/2)
|> Enum.take(5)
end
end
Lazy.answer()
# => [{"that", 2692}, {"with", 1695}, {"this", 1169}, {"from", 1072}, {"have", 752}]

113. # Let’s talk about `mix`

150. # Let’s talk about dependencies

167. # Where to go next?

168. http://exercism.io/

169. http://exercism.io/languages/elixir/about

170. https://adventofcode.com/

171. https://elixirschool.com/en/

172. https://github.com/elixirkoans/elixir-koans

173. https://pragprog.com/book/elixir16/programming-elixir-1-6

174. https://pragprog.com/book/cdc-elixir/learn-functional-programming-with-elixir

175. Thank You!
Pre-bootcamp
introduction to Elixir
Paweł Dawczak