[discussion] arraykey type

Hello Internals, As [Danack](https://github.com/Danack) has mentioned in the [PR comments](https://github.com/php/php-src/pull/4073#issuecomment-487186654), i want to discuss this here before writing an RFC. What do you think about adding the arraykey type to PHP. see : - https://docs.hhvm.com/hack/types/arraykey - https://github.com/php/php-src/pull/4073#issuecomment-487178779 -https://github.com/php/php-src/pull/2603#issuecomment-487122061 - https://twitter.com/azjezz/status/1121182765385433095 - https://www.facebook.com/groups/2204685680/?multi_permalinks=10157789745805681 GitHub pull request : https://github.com/php/php-src/pull/4073 --- ### Weak typing As Nikita [mentioned in the PR](https://github.com/php/php-src/pull/4073#issuecomment-487184224), this is an issue that we are facing even with union types. assuming we have a function named get with the following signature : ``` function get(iterable $container, arraykey $index): mixed; ``` should passing a float or bool be allowed when strict_types=0 ? if so, should get($arr, true); act as get($arr, 1); or get($arr, '1'); ? --- ### Naming The arraykey naming comes from Hack, i found it familiar since i am used to Hack, but we have other options : - index - key - offset --- Best regards, Saif Eddin Gmati.