Functor identity not ===

[marcusradell]

const before = [1,2,3]
const after = before.map(x => x)
before === after // Returns false
for(let i = 0; i < before.length; i++) {
  before[i] === after[i] // Returns true
}
before.length === after.length // Returns true

First equals-check is for the reference, and after is a shallow copy of before. Easiest way to explain might be to write Assert.deepEqual(before, after) and define Assert.deepEqual somewhere so the code still looks minimal.

[jethrolarson]

We could alternatively use ≍ or we could define setoid and use that equals as the way to evaluate equivalence.