misc.

• PEAR PHP Extension and Application Repository
• Xdebug Debugger and Profiler Tool for PHP
  • GitHub

Typing

• PHP Manual
  • Language Reference
    • Types
      • Type System
        • Система типов

Books

• PHP 8 Quick Scripting Reference. A Pocket Guide to PHP Web Scripting by Mikael Olsson

GitHub

• codedokode/pasta: Уроки и черновики для изучающих PHP

Test-Driven Development (TDD)

• Test-Driven Development with PHP 8. Build extensible, reliable, and maintainable enterprise-level applications using TDD and BDD with PHP by Rainier Sarabia - 336 pages

Concurrency

• Хабр / Использование файберов в PHP: разбор от команды СберЗдоровье