What Languages Should Be Included
If you have information about a language that is not on this list, please e-mail me the relevant details. If you can cite a published reference to the language, that will help in determining authenticity. Please remember also that I have a full time job, and won't have a lot of time to devote to tracking down the information myself.
The "Published" Rule - A language should be "published" to be included in this list. There is no precise criterion here, but for example an ad-hoc language devised solely for the compiler course you're taking doesn't count. Even a language that is the topic of a PhD thesis might not necessarily be included. But if material on that language was published in a technical journal or report, or if it formed the basis for additional research, the language belongs in this list. A language does not have to be implemented (actually running as a compiler or interpreter) to be included. Many languages appearing in the ACM SIGPLAN Notices fall in this category.
When there's any doubt, an entry will be included, since we want to make the list as complete as possible. Languages with more widespread use such as C or FORTRAN will generally have more detailed entries.
We've also included some formalisms which are clearly not meant to be used as a source language for writing programs:
For historical completeness, roughly 200 early pre-1959 "automatic programming systems" were included, based on a list from CACM 2(5):16, May 1959. It can be argued that many of these are not really programming languages as the term is used today.