Something between =, == and identical?

[foobar]

Hi folks,

I’m after something like =, == and identical? but neither of those work like I want to.

I would like to write tests that report difference between [1 2 3] and '(1 2 3). Is that possible without using vector??

This doesn’t what I need:

(identical? '(1) '(1))
false

And same for:

(== '(1) '(1))
exception

So I’m using = but sometime it is annoying. For example when output is '([1 2] [3 4]). If something happens and output turns into '((1 2) (3 4)) I would like to know that without testing (first (vector? ....

Thank you.

[John_Newman]

Can you give an example of what test you want to use?

Maybe something like:

(defn same? [& body]
  (and (apply = body)
       (->> body (map type) (apply =))))

#_=> (same? '(1) [1])
false

[Serioga]

Hello @foobar.

Do you want following to be equal or not?

    (list (list 1 2) (list 3 4))
    (list (map identity [1 2]) (map identity [3 4]))

both printed as ((1 2) (3 4)) but elements has different type.

[dave.liepmann]

Welcome

Very similar, very recent thread might be of interest: Equality is a Problem

Regarding why identical? and == aren’t what you want, and this topic in general, Clojure - Equality is good reading if you haven’t yet seen it.

[foobar]

@John_Newman

what test you want to use

Thank you John.

I want to use it in clojure.test only since I understand that I should rather have code that can work with any collection rather than relying on vector / list.

@Serioga

printed as ((1 2) (3 4)) but elements has different type

Good point, thank you Serioga. For testing I’d like to have fn that distinguish between vector, set and everything else (list or what it returned from seq / map). I had a thought about something like (= (str ...) (str ...)) but that would be just sooo wrong ;-).

@dave.liepmann

might be of interest: Equality is a Problem

Thank you Dave. I googled that one and read it. I don’t remember the blog post from the second link but I spent enough time in Clojure (I’m NOT expert but I think I know core principles) to understand that I should not rely on data types. I should rely just on shape of my data. But I was hoping that specifically for clojure.test testing there will be something more than those three functions I know.

[Serioga]

Martin, I suggest to be specific in your tests. You can validate data shape and contents separately like

;; Spec can be used as well to test data shape

(defn valid-elem? [x]
  (and (vector? x)
       (= 2 (count x))))

(defn valid-seq? [xs]
  (and (seq xs)
       (every? valid-elem? xs)))

(let [xs '([1 2] [3 4])]
  (and (valid-seq? xs)
       (= '([1 2] [3 4]) xs)))
#_=> true

(let [xs '('(1 2) '(3 4))]
  (and (valid-seq? xs)
       (= '([1 2] [3 4]) xs)))
#_=> false