Programming Elixir Chapter 13 Notes -

Spent a lot of time Googling in order to complete exercise #4. Wrapping my head around piping and enumeration. Testing helps. Short snippets in LiveBook helps. Practiced documenting.

mix new did not create the ./config directory.
elem accesses a tuple by index.
Elixir builtins
Erlang documentation Application Group sidebar.
Elixir hex
Version control the mix.lock for applications. Review when building a public library.
Mix.Config is deprecated. Use Config
The configuration sets the minimal log level compiled into the application. Code for lower-levels is not even compiled into the application. For example, setting it at :info means you cannot log :debug.
Set the compile-time logging in issues/config/config.exs:
```
config :logger,
   compile_time_purge_level: :info
```
Already outdated, use:
```
config :logger,
  compile_time_purge_matching: [
    [lower_level_than: :info]
  ]
```
The string passed to the log function is always evaluated, even if it is never logged.
Use the function variant when expensive information may not be logged. For example:
```
Logger.debug fn -> "#{expensive(value)}"
```

The documentation to add ex_doc and earmark to the mix.exs development-only and non-runtime flags:

{:ex_doc, "~> 0.27", only: :dev, runtime: false},
{:earmark, "~> 1.14", only: :dev, runtime: false},

Exercises

OrganizingAProject-1

Copied the project as recommended.

OrganizingAProject-2

Added dependency as directed.

OrganizingAProject-3

Sort of duplicated the code.
In playing around with the Poison module I accidentally used encode! instead of parse!, which led me down a rabbit hole of learning how to debug in IEx.

OrganizingAProject-4

My Solution to formatting a table is moderately different from Dave’s. I see where I can improve efficiencies by using map/reduce and doing additional pipelining.

Most importantly, it works!

Reduce a list of maps into a map:

Enum.reduce(list_of_maps, fn x, y ->
  Map.merge(x, y, fn _k, v1, v2 -> v2 ++ v1 end)
end)

Reduce a list of tuples into a map:
```
Enum.into(list, %{})
```

OrganizingAProject-5

Worked through the logging, debugging, and documentation steps. Had made the commandline application earlier.

OrganizingAProject-6

My Solution to the NOAA airport weather lookup.

Needed to add :httpoison and :elixir_xml_to_map to applications.

All notes and comments are my own opinion. Follow me at @rgacote@genserver.social