> Lisp purists will argue M-expressions are unnecessary and S-expressions are all you need.
I would argue that S-Expressions turned out to be extremely practical for developing Lisp software. A layer with different syntax makes it more complex to use.
> Maybe if the M-expression idea had been pursued more seriously, Lisp might be more popular today.
Maybe, maybe not. People have discussed it endlessly, but there is no conclusion.
Currently some people in the Racket community try to make Racket more "popular" (widely used, ...) by providing a new syntax.
Not just practical, S-Expressions are a big part of Lisp's superpowers from a UI perspective. You can manipulate code as forms, not text. It's hard to overstate how much of an advantage that brings to a well-configured editor.
When you start thinking of your program as a nested data structure instead of a text document, you start thinking more clearly - you can manipulate this tree representation directly. This makes molding your program significantly faster, closer to the speed of thought. Wholesale refactoring a function might only take a dozen keystrokes to move the forms (not the chars) around.
I have a hard time going back to the syntactic busywork of manually placing ascii characters like a caveman.
I would argue that S-Expressions turned out to be extremely practical for developing Lisp software. A layer with different syntax makes it more complex to use.
> Maybe if the M-expression idea had been pursued more seriously, Lisp might be more popular today.
Maybe, maybe not. People have discussed it endlessly, but there is no conclusion.
Currently some people in the Racket community try to make Racket more "popular" (widely used, ...) by providing a new syntax.