elixir-notes.md

Elixir

These are shortcuts, commands, and notes about using Elixir.

Debugging from Command Line

Prefix with MIX_DEBUG=1

Recompile Code without Restart

recompile()

.iex.exs

Remember that anything in .iex.exs of project root will get loaded when starting IEx, so useful for test data and the like.

Logical Cores

Automatic parallelism, such as with Task.async*, defaults to the number of logical cores. See the value with

System.schedulers_online()

or

:erlang.system_info(:logical_processors_available)

Get the Last Result

Pass an argument to get specific line number. Defaults to -1, last line.

v()

See Entire Result

IEx by default shortens long results. To get around it,

fun() |> IO.inspect(limit: :infinity)

Abort Syntax Error

If you have some bad syntax in IEx, like a dangling parenthesis or quote, this will dump the statement.

#iex:break

Miscellaneous References

https://paraxial.io/blog/throttle-requests

• https://github.com/michalmuskala/plug_attack

Quick Timing Check

To quickly get a sense of how long something is taking, wrap it in :timer.tc/1. It returns result in μs (microseconds)

{time, result} = :timer.tc(fn ->
  # code to test here
end)

IO.inspect(time, label: :microseconds)
result

Truncate

Dangerous to use, even for testing.

Ecto.Repo.query("TRUNCATE #{Module.Name.__schema__(:source)}", [])

Docs

To output the formatted docs.

h Your.Module.Name

To see the exported functions of a module.

exports Your.Module

Infinit Output in Console

IEx.configure(inspect: [limit: :infinity])