While it's certainly possible to write numerical code in S-expressions, it's often not very pleasant. Compare Julia's "2x^3n - 2y^2 + 1" with the S-expression for the same:
(+ (- (* 2 (^ x (* 3 n))) (* 2 (^ y 2))) 1)
(I think I got that right.) Which would you rather write – or read? Mathematical notation and code tend to lean rather heavily on syntax to lessen the mental burden on the programmer. It's far less egregious but I also prefer `f(x)` to `(f x)`.
In general, we all felt that basic Matlab syntax is pretty good for numerical programming and linear algebra and would actually be fine if you got rid of some of the weirder choices (like indexing with parens and required trailing semicolons).
I do agree that infix syntax for math and array manipulation is more sane. This concerns input parsing (and can be taken care of in Common Lisp too - see the infix reader macro), this wasn't the point of my question.
Did you find that manipulating expressions i.e writing useful macros, with the current expression datastructure in Julia was in some way more efficient than using S-expressions ? Axiom and Maxima have this system where the user predominantly interacts in infix, but for things which require more expressive power, one can switch to lisp (and use the underlying S-expression). I'm thinking about something like writing a macro for generating code for tensor operations. For example something like:
$ @einstein((i j k), C[i, j], A[i, k] * B[k, j])
should be able to generate gemm (forgive my Julia illiteracy).
Oh, having syntax is absolutely an annoyance when writing macros. There's a reason that Lisp is where real macros came from. But it's not so bad – syntax quoting with interpolation helps a lot.
Wouldn't it make sense to switch to S-expressions for the underlying expression structure then (or some sort of automorphism between the two) ? You'll have the misfortune of calling yourself a Lisp, but then you'll have more power :)
In general, we all felt that basic Matlab syntax is pretty good for numerical programming and linear algebra and would actually be fine if you got rid of some of the weirder choices (like indexing with parens and required trailing semicolons).