Primitives for a boring PHP application
Minimalist library of functions and classes to build working applications in (almost) plain PHP.
The current trend in application programming is to add layers of libraries and frameworks over the core language to make development easier. That does increase the abstraction level that the programmer sees, but also leads to leaky abstractions, more stuff to be learned, and more moving/breakable parts that increase complexity.
Besides that, some programming languages are more specialized in certain tasks than others. PHP in particular started as a web templating engine, evolving to a general purpose language over time. I believe that PHP falls short of having most of the features that full-stack frameworks offer.
Being a boring, stable, known technology, PHP is a good choice for many projects. With small additions to the core functions and extensions, it can be used to develop larger applications while keeping maintainability.