IO.puts("Hello, world!")Hello, world!Hello World
Our first program prints the classic message.
Save it as hello-world.exs and run it with
elixir hello-world.exs. No project or compile
step needed: .exs files are scripts.
IO.puts/1 writes a string followed by a newline.
The /1 is the function's arity, its number of
arguments. In Elixir, puts/1 and puts/2 are
different functions.
IO.puts(:stderr, "this goes to standard error")this goes to standard errorIO.inspect/2 prints any value in its Elixir form
and returns it unchanged, so you can drop it into
the middle of an expression to debug it.
[1, 2, 3] |> IO.inspect(label: "list") |> Enum.sum() |> IO.inspect(label: "sum")list: [1, 2, 3]
sum: 6Pitfall:
IO.puts/1wants something printable as text (a string, atom, number, or charlist). For maps, lists of structs and the like, useIO.inspect/2;IO.puts(%{a: 1})raisesProtocol.UndefinedError.