IO.puts("Hello world!")

iex

h

On elixir, functions do not modify values. Functions transforms values on output.

Example :

name = "Toto"
 
if (name == "Toto") do
  IO.puts("Inside condition before being changed: " <> name)
  name = "Robin"
  IO.puts("Inside condition after being changed: " <> name)
end
 
IO.puts("Outside condition after being changed: " <> name)

Output :

Inside condition before being changed: Toto
Inside condition after being changed: Robin
Outside condition after being changed: Toto

Example with date :

d1 = ~D[2023-04-25]
 
IO.puts(d1)
IO.puts(Date.add(d1, 5))
IO.puts(d1)

Output :

2023-04-25
2023-04-30
2023-04-25