Why is the order of haystack and needle inconsistent in PHP functions in_array and strpos?

The order of parameters haystack and needle in these 2 very core PHP functions is not consistent:

http://php.net/manual/en/function.in-array.php (needle, haystack)
http://php.net/manual/en/function.strpos.php (haystack, needle)

Why is this the case?

Solution

Needle/Haystack in PHP

They are actually not inconsistent like many think. You have partly discovered the consistency:

All string functions are (haystack, needle)
All array functions are (needle, haystack)

Rasmus Lerdorf (the creator of PHP) states this in a talk in 2019 around 25 minutes in:

25 Years of PHP - phpday 2019

https://youtu.be/iGOAQli7tGc?t=1485

Inconsistencies in PHP

At 16:45, he has a slide titled "What was he thinking?" and he addresses "naming inconsistencies". (needle/haystack issue is just one of them)

https://youtu.be/iGOAQli7tGc?t=1005

In this talk he also explains that his design decisions for PHP are almost all based on the idea that PHP is a "wrapper for underlying C libraries", and has kept the parameters in the same order as the underlying code.