Variable interpolatable smooth curves and outlines

A bit of an aside...

From the article:

  MetaPost is written in literate programming language WEB, then generating
  Pascal code from it. Hence the tooling and developer experience around
  it is quite suboptimal. Extending it is also almost impossible.

It's unfortunate (and a little funny to me) that a literate programming language, the whole purpose of which is to remain highly maintainable for future generations, is a stumbling block to development. Maybe we need literate build systems, so people can even begin to do development in the language proper? Or maybe the whole "literate" concept harkens from an increasingly-bygone era where it was assumed that a maintainer would spend a long time getting to know the existing system in detail, basically reading a book's-worth of material on the subject as they do their work.