[mkl]

Not enough people agreed. It seems long-abandoned now, but Boa Constructor was it for Python: https://boa-constructor.sourceforge.net/.

Lazarus (quite active) is an open source Delphi clone that I would have been all over in 1996: https://www.lazarus-ide.org/. I haven't been keen on Pascal for a long time though.

Coming from Visual Basic 6 and Delphi, I was awfully disappointed in "Visual" C++.

[squarefoot]

Totally agree on Lazarus: it inherited the "Delphi way" of doing thins, and is a joy to use. For those who never used it, it produces native compiled high performance code (on par with C) and the IDE itself can run for example also on ARM boards, no cross compiling needed. Still dreaming to see it support other languages, but I guess adapting all libraries to them would be a nightmare of a task for a Open Source and Free as in beer project.