https://github.com/laurabeatris/list-length-recursion

Elixir algorithm exercise to practice recursion using tail call optimization
https://github.com/laurabeatris/list-length-recursion

algorithms-and-data-structures elixir functional-programming recursion

Last synced: 20 days ago
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Elixir algorithm exercise to practice recursion using tail call optimization

• Host: GitHub
• URL: https://github.com/laurabeatris/list-length-recursion
• Owner: LauraBeatris
• Created: 2021-10-04T14:05:37.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2021-10-04T16:15:26.000Z (over 3 years ago)
• Last Synced: 2024-11-03T16:42:28.815Z (2 months ago)
• Topics: algorithms-and-data-structures, elixir, functional-programming, recursion
• Language: Elixir
• Homepage:
• Size: 2.93 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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# List Length with Recursion 

Elixir algorithm exercise to practice recursion using [tail call optimization](https://blog.appsignal.com/2019/03/19/elixir-alchemy-recursion.html)

## Interesting Resources

- [Iteration, Recursion, and Tail-call Optimization in Elixir

](https://blog.appsignal.com/2019/03/19/elixir-alchemy-recursion.html)

- [Multi-clause Functions with Pattern Matching and Guards in Elixir

](https://www.culttt.com/2016/05/23/multi-clause-functions-pattern-matching-guards-elixir)

- [Elixir Lists](https://inquisitivedeveloper.com/lwm-elixir-14/)

## Module Usage

```elixir

  ListLength.call([]) # Result: 0

  ListLength.call([1, 2, 3]) # Result: 3

```

## Algorithm Explanation

```elixir

  def call(list), do: get_length(list, 0)

  # Hide the logic with private functions - helps to abstract the logic from the main function

  # Multi-clause functions: overload a function by specifying different clauses to match against - if tail is empty, then return the current accumulator value 

  defp get_length([], acc), do: acc

  # Prepend to a list using the | operator in order to access head and tail - possible due to Elixir nature of having linked lists 

  # Recursively call function and increase accumulator argument until the tail is empty 

  defp get_length([_head | tail], acc), do: get_length(tail, 1 + acc)

```