Day 1

Mix.install([
  {:kino, "~> 0.11.0"},
  {:nimble_parsec, "~> 1.4"}
])

Section

input = Kino.Input.textarea("Input", monospace: true)

defmodule Trebuchet do
  def digit_scan(string, scanner \\ &digit_scan/1)
  def digit_scan("1" <> _rest, _scanner), do: 1
  def digit_scan("2" <> _rest, _scanner), do: 2
  def digit_scan("3" <> _rest, _scanner), do: 3
  def digit_scan("4" <> _rest, _scanner), do: 4
  def digit_scan("5" <> _rest, _scanner), do: 5
  def digit_scan("6" <> _rest, _scanner), do: 6
  def digit_scan("7" <> _rest, _scanner), do: 7
  def digit_scan("8" <> _rest, _scanner), do: 8
  def digit_scan("9" <> _rest, _scanner), do: 9
  def digit_scan(<<_::binary-size(1)>> <> rest, scanner), do: scanner.(rest)

  def forward_scan("one" <> _rest), do: 1
  def forward_scan("two" <> _rest), do: 2
  def forward_scan("three" <> _rest), do: 3
  def forward_scan("four" <> _rest), do: 4
  def forward_scan("five" <> _rest), do: 5
  def forward_scan("six" <> _rest), do: 6
  def forward_scan("seven" <> _rest), do: 7
  def forward_scan("eight" <> _rest), do: 8
  def forward_scan("nine" <> _rest), do: 9
  def forward_scan(string), do: digit_scan(string, &amp;forward_scan/1)

  def reverse_scan("eno" <> _rest), do: 1
  def reverse_scan("owt" <> _rest), do: 2
  def reverse_scan("eerht" <> _rest), do: 3
  def reverse_scan("ruof" <> _rest), do: 4
  def reverse_scan("evif" <> _rest), do: 5
  def reverse_scan("xis" <> _rest), do: 6
  def reverse_scan("neves" <> _rest), do: 7
  def reverse_scan("thgie" <> _rest), do: 8
  def reverse_scan("enin" <> _rest), do: 9
  def reverse_scan(string), do: digit_scan(string, &amp;reverse_scan/1)
end

P1

input
|> Kino.Input.read()
|> String.split()
|> Enum.map(fn calibration_value ->
  Integer.undigits([
    Trebuchet.digit_scan(calibration_value),
    Trebuchet.digit_scan(String.reverse(calibration_value))
  ])
end)
|> Enum.sum()

P2

input
|> Kino.Input.read()
|> String.split()
|> Enum.map(fn calibration_value ->
  Integer.undigits([
    Trebuchet.forward_scan(calibration_value),
    Trebuchet.reverse_scan(String.reverse(calibration_value))
  ])
end)
|> Enum.sum()