Elixir, pattern matching in arguments of named function, simple example

results.ex

defmodule Results do
  def strange_results(%{a: 0} = params) do
    %{params | a: 1000}
  end

  def strange_results(params) do
    params
  end
end

# iex(1)> Results.strange_results(5)
# 5
# iex(2)> Results.strange_results(%{a: 4, b: 5})
# %{a: 4, b: 5}
# iex(3)> Results.strange_results(%{a: 0, b: 5})
# %{a: 1000, b: 5}