Elixir Language Pattern matching Tuples
Example
{ a, b, c } = { "Hello", "World", "!" }
IO.puts a # Hello
IO.puts b # World
IO.puts c # !
# Tuples of different size won't match:
{ a, b, c } = { "Hello", "World" } # (MatchError) no match of right hand side value: { "Hello", "World" }
Reading a File
Pattern matching is useful for an operation like file reading which returns a tuple.
If the file sample.txt contains This is a sample text, then:
{ :ok, file } = File.read("sample.txt")
# => {:ok, "This is a sample text"}
file
# => "This is a sample text"
Otherwise, if the file does not exist:
{ :ok, file } = File.read("sample.txt")
# => ** (MatchError) no match of right hand side value: {:error, :enoent}
{ :error, msg } = File.read("sample.txt")
# => {:error, :enoent}
