[MikeOfAu]

The InterViews library, written by John Vlissides, was for writing GUIs in C++ under X11. It came out in the early 90s. (Yes, I'm an ancient programmer)

He was one of the Gang of Four who wrote Design Patterns, but he wrote this library years before the book came out. It always seemed to me that he invented all the main patterns in the Interviews library before they were subsequently (nicely!) documented in the book (which went on to become a smash hit).

I've since realised that I much prefer functional programming (Clojure!) over OO, BUT, oh my goodness, what a truly groundbreaking and beautiful bit of work it was for its time. I read every line of code in that library, and I became a much better programmer for it.

[AtlasBarfed]

How many amazing GUI libraries and codebases have been discarded over the years?

So much wasted human-centuries of software labor.

I think of things like the PowerBuilder datawindow widget, something that HTML+JS couldn't touch for 15 years until I started to see things like ExtJS and jquery. And it ran on 486s and pentiums.

As for the original question, practically all the superuseful UNIX utils that had to be performant on ancient MHz-class hardware is amazing stuff.