Short Elixir presentation

1. Erlang Elixir|>

2. Elixir
José Valim - co-fondateur de Plataformatec
(http://plataformatec.com.br)
Proposer la puissance de la machine virtuelle Erlang
d’une manière différente aux développeurs.
Premier commit date de janvier 2011
Version actuelle : 0.10.2 / 0.10.3-dev
Release finale est prévue pour juin 2014

3. Erlang :
wget http://www.erlang.org/download/otp_src_R16B02.tar.gz
tar zxf otp_src_R16B02.tar.gz
cd otp_src_R16B02
./configure
make
sudo make install
Elixir :
git clone https://github.com/elixir-lang/elixir.git
cd elixir
make
sudo make install

4. Les variables
Erlang :
• /^(?:_[a-zA-Z0-9_]|[A-Z])[a-zA-Z0-9_]*$/
• single assignment
Elixir :
• /^(?:_[a-zA-Z0-9_]|[a-z])[a-zA-Z0-9_]*$/
• re assignment

5. Erlang :
1> A = [1, 2, 3].
[1, 2, 3]
2> A = [4, 5, 6].
** exception error: no match of right hand side value [4,5,6]
Elixir :
iex(1)> a = [1, 2, 3]
[1, 2, 3]
iex(2)> a = [4, 5, 6]
[4, 5, 6]
Les variables

6. iex(1)> a = [1, 2, 3]
[1, 2, 3]
iex(2)> [b, c, d] = a
[1, 2, 3]
iex(3)> b
1
iex(4)> c
2
iex(4)> d
3

7. iex(1)> a = [1, 2, 3]
[1, 2, 3]
iex(2)> [b | tail] = a
[1, 2, 3]
iex(3)> b
1
iex(4)> tail
[2, 3]

8. atomes
:an_atom
:"an atom!"
booléens
true
false
listes [104,101,108,108,111] = ‘hello’
tuples {1, :tuple, ‘de’, "données"}

9. fonctions
my_fun = fn(x) -> x*x end
my_fun.(3)
regex %r/erlang|elixir/
range [1..10]
hash
[key1: "value1", key2: 3, ...]
[{"Une clé", "sa valeur»}, ...]

10. Les binaires : séquence d’entiers (0-255 / 8 bits)
placée entre << et >>

11. Les binaires : séquence d’entiers (0-255 / 8 bits)
placée entre << et >>
<<104, 101, 108, 108, 111>>

12. Les binaires : séquence d’entiers (0-255 / 8 bits)
placée entre << et >>
<<[104, 101, 108, 108, 111]>>
<<104, 101, 108, 108, 111>>

13. Les binaires : séquence d’entiers (0-255 / 8 bits)
placée entre << et >>
<<[104, 101, 108, 108, 111]>>
<<'hello'>>
<<104, 101, 108, 108, 111>>

14. Les binaires : séquence d’entiers (0-255 / 8 bits)
placée entre << et >>
<<[104, 101, 108, 108, 111]>>
<<'hello'>>
"hello"
<<104, 101, 108, 108, 111>>

15. <<259>> = ?

16. <<259>> = <<3>>

17. <<259>> = <<3>>
<<259:size(16)>> = <<1, 3>>

18. <<259>> = <<3>>
<<259:size(16)>> = <<1, 3>>
<<x:size(16)>> = <<1, 3>>

19. <<2.4>>

20. <<2.4>>
** (ArgumentError) argument error
:erl_eval.expr/3

21. <<2.4>>
<<2.4:float>> =
<<64, 3, 51, 51, 51, 51, 51, 51>>
** (ArgumentError) argument error
:erl_eval.expr/3

22. <<2.4>>
<<2.4:float>> =
<<64, 3, 51, 51, 51, 51, 51, 51>>
** (ArgumentError) argument error
:erl_eval.expr/3
les flottants sont codés sur 64 bits ; le premier bit pour
coder le signe, les 11 suivants pour l’exposant, puis 52
bits pour la mantisse et le dernier, implicite.

23. binary, bits, bitstring, bytes, float,
integer, utf8, utf16, utf32
signed, unsigned
iex(1)> <<f::float, i::[size(32), signed]>> = <<64, 6, 102,
102, 102, 102, 102, 102, 255, 255, 254, 195>>
<<64, 6, 102, 102, 102, 102, 102, 102, 255, 255, 254, 195>>
iex(2)> f
2.8
iex(3)> i
-317

24. defmodule Test do
def circle(t) do
[x|tail] = t
tail ++ [x]
end
end
Test.circle [1, 2, 3]
# => [2, 3, 1]

25. defmodule Test do
def circle(t) do
[x|tail] = t
tail ++ [x]
end
end
Test.circle "123"
** (MatchError) no match of right
hand side value: "123"

26. defmodule Test do
def circle(t) when is_list(t) do
[x|tail] = t
tail ++ [x]
end
end
Test.circle [1, 2, 3]
# => [2, 3, 1]

27. defmodule Test do
def circle(t) when is_list(t) do
[x|tail] = t
tail ++ [x]
end
end
Test.circle "123"
** (FunctionClauseError) no function
clause matching in Test.circle/1

28. defmodule Test do
def circle([x|tail]) do
tail ++ [x]
end
end
Test.circle [1, 2, 3]
# => [2, 3, 1]

29. defmodule Test do
def circle([x|tail]) do
tail ++ [x]
end
end
Test.circle "123"
** (FunctionClauseError) no function
clause matching in Test.circle/1

30. defprotocol Test do
def circle(l)
end

31. defprotocol Test do
def circle(l)
end
defimpl Test, for: List do
def circle(l) do
[x|tail] = l
tail ++ [x]
end
end

32. defprotocol Test do
def circle(l)
end
defimpl Test, for: List do
def circle(l) do
[x|tail] = l
tail ++ [x]
end
end
Test.circle([1, 2, 3])
#=> [2, 3, 1]

33. Test.circle("123")
** (UndefinedFunctionError) undefined
function: Test.BitString.circle/1

34. Test.circle("123")
** (UndefinedFunctionError) undefined
function: Test.BitString.circle/1
defimpl Test, for: BitString do
def circle(l) do
[x|tail] = String.to_char_list!(l)
list_to_bitstring(tail ++ [x])
end
end

35. Test.circle("123")
** (UndefinedFunctionError) undefined
function: Test.BitString.circle/1
defimpl Test, for: BitString do
def circle(l) do
[x|tail] = String.to_char_list!(l)
list_to_bitstring(tail ++ [x])
end
end
Test.circle("123")
#=> "231"

36. defmodule Test do
defmacro times(n, body) do
quote do:
Enum.each(
1..unquote(n),
fn(_) -> unquote(body) end
)
end
end
require Test
Test.times(10) do
IO.puts "hello"
end
# => hello 10 times

37. Process
defmodule Math do
def sum do
receive do
{:sum, a, b} ->
IO.puts "#{a} + #{b} = #{a+b}"
sum()
_ -> IO.puts "not implemented!"
end
end
end
pid = spawn(fn -> Math.sum end)
pid <- {:sum, 4, 7}
# => 4 + 7 = 11
pid <- {:mult, 4, 7}
# => not implemented!

38. |>
x = [1, 2, 3, 4]
x = Enum.filter(x, fn(e) -> rem(e, 2) == 0 end)
x = Enum.reduce(x, 0, fn(e, r) -> e + r end)

39. |>
x = [1, 2, 3, 4]
x = Enum.filter(x, fn(e) -> rem(e, 2) == 0 end)
x = Enum.reduce(x, 0, fn(e, r) -> e + r end)
x = [1, 2, 3, 4]
|> Enum.filter(fn(e) -> rem(e, 2) == 0 end)
|> Enum.reduce(0, fn(e, r) -> e + r end)

40. |>
x = [1, 2, 3, 4]
x = Enum.filter(x, fn(e) -> rem(e, 2) == 0 end)
x = Enum.reduce(x, 0, fn(e, r) -> e + r end)
x = [1, 2, 3, 4]
|> Enum.filter(fn(e) -> rem(e, 2) == 0 end)
|> Enum.reduce(0, fn(e, r) -> e + r end)
x = [1, 2, 3, 4]
|> Enum.filter(&(rem(&1, 2) == 0))
|> Enum.reduce(0, &(&1 + &2))

41. Mix
mix new my_app
cd my_app
mix deps.get
mix compile
mix test

42. Web
• cowboy : http://ninenines.eu
• dynamo : https://github.com/elixir-lang/dynamo
• weber : http://0xax.github.io/weber/

43. Resources
http://elixir-lang.org
https://github.com/glejeune/ews