Pattern Matching in Elixir

links: Functions in Elixir

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The use of pattern matching is dominant in assertive, idiomatic Elixir code. When using the match operator, if the pattern on the left matches the right, any variables on the left are bound, and the value of the right side is returned. A matchError is raised if there is no match

{_, denominator} = Float.ratio(0.25)
# => {1, 4}
# The variable `denominator` is bound to the value 4

Pattern Matching in Named Functions

Pattern matching is also a useful tool while creating multiple function clauses. Pattern matching can also be used on the function’s arguments, which determines which function clause to invoke — from the top of the file down until the first match. Variables maybe bound in a function head and used in the function body

defmodule Example do
  def named_function(:a = variable_a) do
    {variable_a, 1}
  end
 
  def named_function(:b = variable_b) do
    {variable_b, 2}
  end
end
 
Example.named_function(:a)
# => {:a, 1}
 
Example.named_function(:b)
# => {:b, 2}
 
Example.named_function(:c)
# => ** (FunctionClauseError) no function clause matching in Example.named_function/1

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tags: elixir function patterns sources:

• Exercism syllabus pattern matching