An abundance of programming languages

For 50 years, computer programmers have been writing code. New technologies continue to emerge, develop, and mature at a rapid pace. Now there are more than 2,500 documented programming languages! O'Reilly has produced a poster called History of Programming Languages, which plots over 50 programming languages on a multi-layered, color-coded timeline.

It's fun to look at, but unfortunately rather incomplete in the particulars and connections of the illustrated languages. Some little-recognized languages were designed to restrain an unwelcome proliferation of custom languages and compilers, and to collect best practices and state-of-the-art at given times. The facts around that would make for a more interesting story.