I can't articulate this idea, because I'm not well versed enough in programming language implementation. Maybe some forth or lisp folks can help me. A programmi

I can't articulate this idea, because I'm not well versed enough in programming language implementation. Maybe some forth or lisp folks can help me. A programming language can be very minimal, which is great. But it does reach a certain minimum possible complexity with regard to syntax. It has to have either a toggle to switch from 'execute mode' into 'compile mode' a la forth's `:` operator, or it has to have a particular syntax difference between 'defining a function' versus 'call a function'. I'm not sure if this is true. Does lisp have such a difference, or is everything just function application all the way down? This idea is stuck in my head. Can anybody recommend a book or formal terminology for what I'm getting at here?