Hi,
I've been evaluating clojure with a bias around performance (I do a lot of
numerical work). I don't need to the metal, but want to see that fundamental
operations are comparable to java in performance and that performance can be
had not at the expense of conciseness. In particular, I've noted that
arithmetic such as:
(+ a b c d)
is not equivalent to:
(+ (+ (+ a b) c) d)
in performance, because the former form applies + on a list or array form (I
forget which). This is regardless of whether all of the above values have
primitive type hints. At least this is what I observe in debugging (correct
me if I am wrong).
Could + and other operators be changed to a macro mapping rather than the
current defn, mapping the argument list to a binary expression tree (+ (+ (+
... instead of the list style application (I'm guessing yes, not being
familiar with CL-style macros).
Secondly, if one has code like:
(let [
x (int a)
y (int b)]
(+ (* x 2) (* y 3) (* x y 5))
(* x 2) -> a function of (int, Object), as the literal 2 is not assumed to be
a primitive type. This instead needs to be mapped to:
(let [
x (int a)
y (int b)]
(+ (+ (* x (int 2)) (* y (int 3)) (* (* x y) (int 5))))
I don't know if type hints can be interrogated or known at the time of macro
evaluation (I'm guessing not), but if so, would like to see that in such a
macro.
Automatically decorating literals that are used in the context of arithmetic
with a primitive would make clojure a lot more usable for performance-concerned
arithmetic.
I think I saw mention that #^int (and other primitive types) will be supported
at some point in argument declarations as well?
Thanks
Jonathan
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