> Lambda calculus is a BFD in the subfield of programming languages
This is a good example of abusing the vocabulary of mathematics as is common in the FP world. A programming language is not an object in abstract algebra. You can't add, subtract, or factorize a programming language. It's just software.
That is very debatable.
Lambda calculus is a BFD in the subfield of programming languages, which is the topic at hand.