Programmer's Notepad is not available for Mac but there are plenty of alternatives that runs on macOS with similar functionality. The best Mac alternative is Vim, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Programmer's Notepad and loads of them is available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to Programmer's Notepad are Eclipse (Free, Open Source), VSCodium (Free, Open Source), Geany (Free, Open Source) and gedit (Free, Open Source).
GNU nano is a small and friendly text editor. Besides basic text editing, nano offers many extra features like an interactive search and replace, go to line and column number, auto-indentation, feature toggles, internationalization support, and filename tab completion.
Neovim is a project that seeks to aggressively refactor Vim in order to: Simplify maintenance and encourage contributions. Split the work between multiple developers. Enable the implementation of new/modern user interfaces without any modifications to the core source.
Bluefish is a powerful editor targeted towards programmers and webdesigners, with many options to write websites, scripts and programming code. Bluefish supports many programming and markup languages, and it focuses on editing dynamic and interactive websites.
CudaText is a cross-platform text editor, written in Lazarus. It starts quite fast (0.5 sec with ~30 plugins on CPU Intel Core i3 3Hz). It is extensible by Python add-ons (plugins, linters, code tree parsers, external tools).