Monkey is not an official language and has no official specification. It is a toy language that is used to teach the basics of writing an interpreter. You can read more about the Monkey language and see other implementations Monkey: The programming language that lives in books.
Installation
go install github.com/solbero/monkey@latest
Usage
$ go run main.go
Hello mrnugget! This is the Monkey programming language!
Feel free to type in commands
>> let answer = 6 * 7;
>> answer;
42