What are the breaking changes in clojure 1.3?

Question

I have been having trouble keeping up with the list of changes in 1.3 and most importantly the changes that require me to change my code.

• What has changed,
• what is about to change,
• where can I get up to date lists of these?

Answer 1

Breaking changes to date:

• Math ops no longer promote into bignums.

• Math ops no longer narrow the result to the smallest type that can hold them.

• Vars will no longer default to being dynamically bindable. Add ^:dynamic when needed.

Answer 2

A couple of other numerical changes:

• There is a new literal for BigIntegers: 5N, which is 5 as a BigInteger.
• The rules for equality have changed (perhaps arising as a result of the changes Alex mentions?):
  • (= 2 2.0) => false, but (== 2 2.0) => true
  • (= 2 2M) => false, but (== 2 2M) => true
  • (= 2.0 2M) => false, but (== 2.0 2M) => true
  • and for clarity:
    • (= 2 2N) => true
    • (= 2 4/2) => true
  • You can generally assume that you'll need == to compare floating-point numbers for equality (which is still probably a shaky proposition).