Multi-Head Functions

Pattern Matching in Function Heads

Elixir allows multiple clauses for the same function, each matching different patterns:

defmodule Handler do
  def handle({:ok, value}), do: "Success: #{value}"
  def handle({:error, reason}), do: "Error: #{reason}"
  def handle(_), do: "Unknown"
end

Elixir tries each clause top to bottom until one matches.

Using It

IO.puts(Handler.handle({:ok, 42}))          # Success: 42
IO.puts(Handler.handle({:error, "not found"}))  # Error: not found
IO.puts(Handler.handle(:something_else))    # Unknown

This pattern is fundamental to Elixir — it replaces if/else chains with declarative matching.

Your Turn

Implement the Handler module above and print all three results.