Tcl
Tcl is a dynamic programming language known for its simplicity and flexibility. It is commonly used for writing scripts, creating GUI applications, and embedding into larger systems as a scripting interface.
Hello, world code example:
puts stdout {Hello world!}
Popularity: Less than 1% of developers are using or have used this language.*
*According to StackOverflow's 2023 survey.
Repositories on GitHub: 17,657