Elixir Cheat sheet

elix_tut.ex

# Vikram March 28, 2018
# Based on video on elixir by Derek
# commands to run: iex, c("elix_tut.ex"), M.main
defmodule M do
  def main do
    # string_stuff()
    # math_stuff()
    # compare_stuff()
    # decision_stuff()
    # tuple_stuff()
    # list_stuff()
    # map_stuff()
    # pattern_stuff()
    # anonymous_function()
    # recursion_stuff()
    # loop_stuff()
    # enum_stuff()
    # error_stuff()
    # additional_stuff()
    concurrency_stuff()
  end

  def concurrency_stuff do
    spawn(fn() -> loop(50, 1) end)
    spawn(fn() -> loop(100, 50) end)

    send(self(), {:french, "Vikram"})

    receive do
      {:german, name} -> IO.puts("Guten tag #{name}")
      {:french, name} -> IO.puts("Bonjour #{name}")
      {:english, name} -> IO.puts("Hello #{name}")
    after
      500 -> IO.puts "Time up"
    end
  end

  def error_stuff do
    err = try do
      5 / 0
    rescue
      ArithmeticError -> "Cant divide by Zero"
    end

    IO.puts err
  end

  def additional_stuff do
    dbl_list = for n <- [1,2,3], do: n*2
    IO.inspect dbl_list

    even_list = for n <- [1,2,3,4], rem(n, 2) == 0, do: n
    IO.inspect even_list
  end

  def enum_stuff do
    IO.puts "Even list: #{Enum.all?([1, 2, 3], fn(n) -> rem(n, 2) == 0 end)}"
    IO.puts "Even list any: #{Enum.any?([1, 2, 3], fn(n) -> rem(n, 2) == 0 end)}"
    Enum.each([1, 2, 3], fn(n) -> IO.puts n end)

    dbl_list = Enum.map([1,2,3], fn(n) -> n*2 end)
    IO.inspect dbl_list

    sum_vals = Enum.reduce([1,2,3], fn(n, sum) -> n+sum end)
    IO.puts "Sum: #{sum_vals}"

    IO.inspect Enum.uniq([1,2,2,3,3])
  end

  def loop_stuff do
    IO.puts "Sum: #{sum([1, 2, 3])}"
    loop(5, 1)
  end

  def sum([]), do: 0

  def sum([h|t]), do: h + sum(t)

  def loop(0, _), do: nil

  def loop(max, min) do
    if max < min do
      loop(0, min)
    else
      IO.puts "Num: #{max}"
      loop(max - 1, min)
    end
  end

  def recursion_stuff do
    IO.puts "factorial of 4 is : #{factorial(4)}"
  end

  def factorial(num) do
    if num <= 1 do
      1
    else
      res = num * factorial(num - 1)
      res
    end
  end

  def anonymous_function do
    get_sum = fn (x, y) -> x+y end
    IO.puts "5 + 4 = #{get_sum.(5, 4)}"

    get_less = &(&1 - &2)
    IO.puts "4 - 2 = #{get_less.(4, 2)}"

    add_sum = fn
      {x, y} -> IO.puts "#{x} + #{y} = #{x+y}"
      {x, y, z} -> IO.puts "#{x} + #{y} + #{z} = #{x+y+z}"
    end
    add_sum.({1, 2, 3})
    add_sum.({1, 2})

    IO.puts do_it()
  end

  # fn with default values for arguments
  def do_it(x \\ 1, y \\ 1) do
    x + y
  end

  def pattern_stuff do
    [_, [_, a]] = [10, [20, 30]]
    IO.puts "a is #{a}"
  end

  def map_stuff do
    capitals = %{"UP" => "Lucknow", "Haryana" => "Chandigarh"}
    IO.puts "Capital of UP is #{capitals["UP"]}"

    capitals2 = %{up: "Lucknow", haryana: "Chandigarh"}
    IO.puts "Capital of Haryna is #{capitals2.haryana}"

    capitals3 = Dict.put_new(capitals, "Tamilnadu", "Chennai")
    IO.inspect capitals3
  end

  def list_stuff do
    list1 = [1,2,3]
    list2 = [4,5,6]
    list3 = list1 ++ list2
    list4 = list3 -- list1

    IO.puts 6 in list4

    [head | tail] = list3
    IO.puts "head: #{head}"

    IO.write "Tail: "
    IO.inspect tail

    IO.inspect [97, 98]
    IO.inspect [97, 98], charlists: :as_lists

    Enum.each tail, fn item ->
      IO.puts item
    end

    display_list(["This", "is", "a", "sentence"])

    IO.inspect List.delete(list3, 4)
    IO.inspect List.delete_at(list3, 0)
    IO.inspect List.insert_at(list3, 0, 9)
    IO.puts List.first(list3)
    IO.puts List.last(list3)

    another_list = [name: 'vikash', height: 6.1]
    IO.inspect another_list
  end

  def display_list([word | words]) do
    IO.puts word
    display_list(words)
  end

  def display_list([]), do: nil

  def tuple_stuff do
    my_stats = {183.5, 6, :"Vikash Vikram"}
    IO.puts "tuple: #{is_tuple(my_stats)}"

    my_stats2 = Tuple.append(my_stats, 34)
    IO.puts "age: #{elem(my_stats2, 3)}"

    IO.puts "Size: #{tuple_size(my_stats2)}"

    my_stats3 = Tuple.delete_at(my_stats2, 0)

    my_stats4 = Tuple.insert_at(my_stats3, 0, 1984)

    many_zeroes = Tuple.duplicate(0, 5)

    {weight, height, name} = {85, 6.1, "Vikash Vikram"}
    IO.puts "weight: #{weight}"
  end

  def string_stuff do
    IO.puts "Equals: #{"Egg" === "egg"}"
    my_str = "Sentence"
    IO.puts "Length: #{String.length(my_str)}"
    longer_string = my_str <> " " <> "is longer"
    IO.puts "My ? #{String.contains?(longer_string, "is")}"
    IO.puts "First: #{String.first(longer_string)}"
    IO.puts "Index 4: #{String.at(longer_string, 4)}"
    IO.puts "Substring: #{String.slice(longer_string, 4, 10)}"

    IO.inspect String.split(longer_string, " ")
    IO.puts String.reverse(my_str)
    IO.puts String.upcase(longer_string)
    IO.puts String.downcase(longer_string)
    IO.puts String.capitalize(longer_string)

    4 * 10 |> IO.puts
  end

  def math_stuff do
    IO.puts "5 + 4 = #{5+4}"
    IO.puts "5 - 4 = #{5-4}"
    IO.puts "5 * 4 = #{5*4}"
    IO.puts "5 / 4 = #{5/4}"
    IO.puts "5 div 4 = #{div(5, 4)}"
    IO.puts "5 rem 4 = #{rem(5, 4)}"
  end

  def compare_stuff do
    IO.puts "4 == 4.0 : #{4 == 4.0}"
    IO.puts "4 === 4.0 : #{4 === 4.0}"
    IO.puts "4 != 4.0 : #{4 != 4.0}"
    IO.puts "4 !== 4.0 : #{4 !== 4.0}"

    age = 16
    IO.puts "Vote and Drive: #{(age >= 16) and (age >= 18)}"
    IO.puts "Vote or Drive: #{(age >= 16) or (age >= 18)}"
    IO.puts not true
  end

  def decision_stuff do
    age = 16
    if age >= 18 do
      IO.puts "You can Vote"
    else
      IO.puts "You can't Vote"
    end

    unless age === 18 do
      IO.puts "You are not 18"
    else
      IO.puts "You are 18"
    end

    cond do
      age >= 18 -> IO.puts "You can vote"
      age >= 16 -> IO.puts "You can drive"
      age >= 14 -> IO.puts "You can wait"
      true -> IO.puts "default"
    end

    case 2 do
      1 -> IO.puts "Entered 1"
      2 -> IO.puts "Entered 2"
      _ -> IO.puts "default"
    end

    IO.puts "Ternary: #{if age > 18, do: "Can vote", else: "Can't vote"}"
  end
end