Elixir 101

Basic

# variable
a = 1
a

# 255 -> 25.5
IO.puts(0xff / 10)

# octal, 8 + 1 = 9
IO.puts(0o11) 

# binary, 4 + 1
IO.puts(0b0101)

# round, floor, ceil
IO.puts(round(3.58))
IO.puts(floor(1.2))
IO.puts(ceil(3.4))

# is_integer
IO.puts(is_integer(1))
IO.puts(is_float(1))
IO.puts(is_atom(1))
IO.puts(is_atom(:halo))

IO.puts(:halo) # atom

IO.puts(true and false)
IO.puts(false and false)
IO.puts(false or true)
IO.puts(true or false)

# left side will be processed first
IO.puts(1 || :ok)
IO.puts(:ok || 1)

IO.puts("hello " <> "world, ALDI!!")

add = fn a, b -> a + b end
add.(2, 5)

# high order function
fnc = fn cb, default -> cb.(default, 2) end
fnc.(add, 1)

dbx = fn x -> x * 2 end

# hof over the loop
Enum.each([
  add.(2, 1), fnc.(add, fnc.(add, 1))
], fn x -> IO.puts("Item: #{x}") end)

# with hof for doubling number
doubled_numbers = for x <- [1, 2, 3], do: dbx.(x)
IO.inspect(doubled_numbers)

# 0 + doubled numbers from reducer
total_doubled_tuples = Enum.map_reduce([1,2,3], 0, fn x, acc -> {dbx.(x), x + acc} end)
{doubled_list, accum} = total_doubled_tuples
accum

# head and tail
[h | t] = [10, 9, 8, 7, 6, 5, 4]
IO.inspect("head: #{h}")
IO.inspect(t)

defmodule Greeter do
  def hello(n \\ nil) # default value to set n to nil
  # def hello(nil), do: hello("") # explicitly
  def hello("Aldi"), do: "Hello Aldi!"
  def hello("Paidy"), do: "Oh hey, Paidy!"
  def hello(n) when n == "", do: "Hola, desconocido!" # using guard clause
  def hello(n) when is_binary(n) and byte_size(n) > 5, do: "Hola, #{n}!!!!"
  def hello(_), do: "Halo, who r u?"
end

name = "Paidy"
IO.puts(Greeter.hello("Goldi")) # with \r
IO.puts(Greeter.hello("Aldiwildan"))
IO.puts(Greeter.hello("Aldi"))
IO.puts(Greeter.hello()) # nil
IO.write(Greeter.hello(name)) # no \r

# if else

n = 10

if n > 3 do
  IO.puts("n is greater than 3")
end

# odd even
if rem(add.(1, 10), 10) == 2 do
  IO.puts("n is even")
else 
  IO.puts("n is odd")
end

# switch case 
defmodule Number do
  def check_number(n) do
    case n do
      0 -> "Zero"
      1 -> "One"
      x when x > 1 -> "Positive number"
      _ -> "Negative number"
    end
  end

  def check(n) do
    cond do
      n == 0 -> "Zero"
      n < 0 -> "Negative Number"
      n > 1 -> "Positive Number"
      true -> "Small positive number"
    end
  end

  def is_odd(n) do
    if rem(n, 2) == 1 do 
      true
    end
    false
  end

  def is_even(n) do
    if rem(n, 2) == 0 do
      true
    end
    false
  end
end

IO.puts(Number.check_number(1))   # "One"
IO.puts(Number.check_number(-5))  # "Negative number"
IO.puts(Number.check_number(10))  # "Positive number"
IO.puts("")
IO.puts(Number.check(1))
IO.puts(Number.check(-5))
IO.puts(Number.check(10))
IO.puts("")
IO.puts("is 1 an even number? #{Number.is_even(1)}")
IO.puts("is 2 an even number? #{Number.is_even(2)}")
IO.puts("")
IO.puts("is 1 an odd number? #{Number.is_odd(1)}")
IO.puts("is 2 an odd number? #{Number.is_odd(2)}")