4 ms·

I assume you mean persistent, not immutable. a[x] = 1 b = a a[y] = 2 <---- mutates a a[x] = 3 <-- is this legal? b[x] <--- persistent-

• programnature 12y ago
  No, I meant lists of rules like {a->1,b->2}, which capture the same kind of patterns as in the previous example but in an immutable (and copy-on-write) way.
• taliesinb 12y ago
  Yes, Associations use the same basic algorithm as Scala and Clojure's hashmaps, and are indeed persistent. And b[x] there gives 1 as you would expect.
  • davorak 12y ago
    Do you know when that change was put into place? I have been using Mathematica sense version 5 and my intuition was that `b[x] == 3`. Testing in mathematica 8 which I have on hand confirms this.
    • taliesinb 12y ago
      Mathematica 8 doesn't have associations, so you must be testing symbol assignments. Write a = <||> before running the above code to test this on associations; associations are persistent, the symbol table is not.