# Parameter pattern matching

**URL:** <https://forum.elixirforum.com/t/parameter-pattern-matching/14173>\
**Category:** Questions\
**Tags:** pattern-matching, function-clause\
**Created:** [May 12, 2018, 1:25pm UTC](https://forum.elixirforum.com/t/parameter-pattern-matching/14173 "2018-05-12T13:25:11Z")\
**Posts on this page:** 1\
**Showing post:** 3

<div class="post-metadata">

**Author:** ![dom](https://forum.elixirforum.com/user_avatar/forum.elixirforum.com/dom/32/9313_2.png) [@dom](https://forum.elixirforum.com/u/dom)\
**Post date:** [May 12, 2018, 1:37pm UTC](https://forum.elixirforum.com/t/parameter-pattern-matching/14173/3 "2018-05-12T13:37:25Z")

</div>

It’s explained here: [https://elixir-lang.org/getting-started/pattern-matching.html](https://elixir-lang.org/getting-started/pattern-matching.html)

```
If a variable is mentioned more than once in a pattern, all references should bind to the same pattern:
iex> {x, x} = {1, 1}
{1, 1}
iex> {x, x} = {1, 2}
** (MatchError) no match of right hand side value: {1, 2}

```

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