Miranda
Miranda is a high-level functional programming language known for its simplicity and elegance, often used for teaching and research in functional programming concepts. Its main uses include functional programming education, prototyping, and language research.
Hello, world code example:
main :: [sys_message]
main = [Stdout "Hello, world!\n"]
Popularity: Less than 1% of developers are using or have used this language.*
*According to StackOverflow's 2023 survey.