Inspect with Label

IO.inspect returns the value you pass in as the first argument. This is great when you want to debug the middle state of a series of piped calls.

"ABCDEFG"
|> String.graphemes
|> Enum.each_with_index
|> IO.inspect
|> Enum.map(fn({letter, i}) -> "#{letter}#{i}" end)
|> Enum.join

Here, inspect will write to stdout the values [{"A", 1}, {"B", 2"}...].

IO.inspect also takes a label option, which decorates the values written to stdout but does not disrupt the piped calls.

"ABCDEFG"
|> String.graphemes
|> Enum.each_with_index
|> IO.inspect(label: "Letters with index:")
|> Enum.map(fn({letter, i}) -> "#{letter}#{i}" end)
|> Enum.join

Which outputs Letters with index: [{"A", 1}, {"B", 2"}...] to stdout.