danj3

# Build And Package

Live meeting 2sep 25

# Priority issues rebar3

1. issues with using hex deps to compile
2. locking of plugins for non default profiles
3. windows may be broken, CI says it is but that may only be CI
4. relx on windows is in a questionable state

danj3

Silly Macros

Mix.install([
  {:kino, "~> 0.16.0"}
])

Data

danj3

defmodule ElmdbStage do
  @moduledoc """
  Create a GenStage for an :elmdb based LMDB database cursor.
  This is for linearly reading from a db
  """
  use GenStage

  def start_link( env, db ) do
    GenStage.start_link( __MODULE__, { env, db } )
  end

danj3

defmodule HashSignature do
  @doc """
    encode input to a sha256 and output as an armored string.
    results should be fully portable and consistent with other
    tools.
  """
  def get( input ) do
    :crypto.hash( :sha256, input )
    |> :crypto.bytes_to_integer
    |> (fn i -> :io_lib.format("~64.16.0b",[i]) |> hd end ).()

danj3

defmodule TimeAgent do

  def start_link do
    Agent.start_link( fn -> { Map.new, Map.new } end, name: __MODULE__ )
  end
  
  def time_run( m, f, a ) do
    { us, result } = :timer.tc( m, f, a )
    Agent.cast( __MODULE__, __MODULE__, :add_sample, [ to_string(m) <> "." <> to_string(f), us ] )
    result

danj3

defmodule TermRoundTrip do
  @moduledoc """
  Convert a term to a readable string then back to a term
  """

  def term_to_binary( term ) do
    :io_lib.format("~p.~n", [ term ] )
    |> :erlang.iolist_to_binary
  end

danj3

  defmodule Day4 do
    def parser( input ) do
      String.split( input, "\n" )
      |> Enum.reduce( [], fn "", acc -> acc; line,acc -> [ String.split(line," ") | acc ] end )
    end

    def start1( input ) do
      parser( input ) |> step1a( [valid: 0, invalid: 0] )
    end

danj3

  defmodule Day3 do
    # This does more work than required but is still O(1)
    # diagonal low right is even square root                                                           
    def start1( val ) do
      col_height = :math.sqrt( val ) |> Float.ceil |> trunc
      col_height = if Integer.mod( col_height, 2 ) == 0, do: col_height+1, else: col_height
      low_right_corner = :math.pow( col_height, 2 ) |> trunc
      distance = low_right_corner - val
      ring_length = col_height * 4 - 4

danj3

  defmodule Day2 do
    def parser( input ) do
      String.split( input, "\n" )
      |> Enum.map( fn k ->
        String.split( k, "\t")
        |> Enum.map( &String.to_integer/1 )
      end )
    end
    def start1( input ) do
      input

danj3

defmodule TimeoutExample do
 use GenServer
 def init(_args), do: {:ok, 0, 5_000}
 def handle_info(:timeout, state) do   
   IO.inspect(state)
   {:noreply, state+1, 5_000 + state*1000}
 end
end

iex> {:ok, p} = GenServer.start(TimeoutExample, [])