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On REPL, if I define
(def fits (map vector (take 10 (iterate inc 0)))) and then call
(== [2] (nth fits 2)) I get false.
But
(= [2] (nth fits 2)) returns true.
Is this expected ? I tried (class [2]) and (class (nth fits 2) and both return Persistent Vector.
756
Unlike Java's equals method, Clojure's = returns true for many values that do not have the same type as each other. = does not always return true when two numbers have the same numeric value. If you want to test for numeric equality across different numeric categories, use == .
Advertisements. A Vector is a collection of values indexed by contiguous integers. A vector is created by using the vector method in Clojure.
Clojure let is used to define new variables in a local scope. These local variables give names to values. In Clojure, they cannot be re-assigned, so we call them immutable.
== is for comparing numbers. If either of its arguments is not a number, it will always return false:
(== :a :a) ; => false As you can see by saying (clojure.contrib.repl-utils/source ==) at the REPL (with repl-utils require'd, of course), == calls the equiv method of clojure.lang.Numbers. The relevant bit of clojure/lang/Numbers.java (from the latest or close-to-latest commit on GitHub):
static public boolean equiv(Object x, Object y){ return y instanceof Number && x instanceof Number && equiv((Number) x, (Number) y); } Use = for equality comparisons of things which may not be numbers. When you are in fact dealing with numbers, == ought to be somewhat faster.
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== is a type independent way of comparing numbers
(== 3 3.0) ;=> true (= 3 3.0) ;=> false If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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