outline basic build and watch tasks

lib/mix/tasks/site.build.ex

@@ -0,0 +1,13 @@
+defmodule Mix.Tasks.Site.Build do
+  @moduledoc "Build and output the site as HTML"
+  @shortdoc "build the site"
+  use Mix.Task
+
+  alias SloaneSH.Format
+
+  @impl Mix.Task
+  def run(_args) do
+    {micro, :ok} = :timer.tc(&SloaneSH.build/0)
+    IO.puts("built site in #{Format.time(micro)}")
+  end
+end

lib/mix/tasks/site.watch.ex

@@ -0,0 +1,26 @@
+defmodule Mix.Tasks.Site.Watch do
+  @moduledoc "Build and output the site as HTML watching for changes"
+  @shortdoc "build the site and watch for changes"
+  use Mix.Task
+
+  @impl Mix.Task
+  def run(_args) do
+    IO.puts("Starting site.watch...")
+
+    {:ok, pid} = SloaneSH.watch()
+
+    unless iex_running?() do
+      ref = Process.monitor(pid)
+
+      receive do
+        {:DOWN, ^ref, _, _, _} ->
+          IO.puts("site.watch terminated")
+          :ok
+      end
+    end
+  end
+
+  defp iex_running? do
+    Code.ensure_loaded?(IEx) and IEx.started?()
+  end
+end

lib/sloane_sh.ex

@@ -2,4 +2,14 @@ defmodule SloaneSH do
   @moduledoc """
   Sloane's personal static site generator powering [sloane.sh](https://sloane.sh).
   """
+
+  def build(_opts \\ []) do
+    :ok
+  end
+
+  def watch(_opts \\ []) do
+    Task.start_link(fn ->
+      Process.sleep(5_000)
+    end)
+  end
 end

lib/sloane_sh/format.ex

@@ -0,0 +1,34 @@
+defmodule SloaneSH.Format do
+  @moduledoc """
+  Functions to format various literals into human readable forms.
+  """
+
+  @millisecond 1000
+  @second @millisecond ** 2
+  @minute 60 * @second
+  @hour 60 * @minute
+
+  @max_depth 2
+
+  def time(micro, depth \\ 0)
+  def time(_micro, depth) when depth >= @max_depth, do: []
+
+  time_units = [
+    {@hour, "h"},
+    {@minute, "m"},
+    {@second, "s"},
+    {@millisecond, "ms"}
+  ]
+
+  for {division, unit} <- time_units do
+    def time(micro, depth) when micro >= unquote(division) do
+      count = "#{div(micro, unquote(division))}#{unquote(unit)}"
+      rem = rem(micro, unquote(division))
+      [count, time(rem, depth + 1)]
+    end
+  end
+
+  def time(micro, _depth) do
+    "#{micro}μs"
+  end
+end