people.exs

# my blog  : https://trangell.com/fa/
# public : http://iranonrails.ir

people = [
  %{ name: "Grumpy",    height: 1.24 },
  %{ name: "Dave",      height: 1.88 },
  %{ name: "Dopey",     height: 1.32 },
  %{ name: "Shaquille", height: 2.16 },
  %{ name: "Sneezy",    height: 1.28 }
]

defmodule HotelRoom do

  def book(%{name: name, height: height})
  when height > 1.9 do
    IO.puts "Need extra long bed for #{name}"
  end

  def book(%{name: name, height: height})
  when height < 1.3 do
    IO.puts "Need low shower controls for #{name}"
  end

  def book(person) do
    IO.puts "Need regular bed for #{person.name}"
  end

end

people |> Enum.each(&HotelRoom.book/1)
# Enum.each(people, fn(x) -> HotelRoom.book(x) end)


#   Need low shower controls for Grumpy
#   Need regular bed for Dave
#   Need regular bed for Dopey
#   Need extra long bed for Shaquille
#   Need low shower controls for Sneezy


# good

%{2 => state} = %{ 1 => :ok , 2 => :error } 
state

# error
%{ item => :ok } = %{ 1 => :ok , 2 => :error }


# pin operator

iex(7)> data = %{ name: "shahryar" , state: "Tx", likes: "Swift" }
%{likes: "Swift", name: "shahryar", state: "Tx"}
iex(8)> for key <- [ :name, :likes ] do                           
...(8)> %{^key => value } = data                                  
...(8)> value                                                     
...(8)> end                                                       
["shahryar", "Swift"]

# update map

new_map %{old_map | key => value.. }

m = %{ a: 1, b: 2 , c: 3 }
%{ a: 1, b: 2 , c: 3 }

m1 = %{ m | b: "two" , c: "three" }
%{ a: 1, b: "two" , c: "three" }


m2 = %{ m1 | a: "one"}
%{a: "one", b: "two", c: "three" }