Array.prototype.map() in javascript doesn't preserves integrity

[jonasporto]

I think that Array map method surprisingly doesn't apply as example of Functor

var a = [1, 2 , 3]; a.map(x => x) === a // false

the same for const b = [1, 2, 3]; b.map(x => x) === b // false

[jethrolarson]

Yeah we shouldn't use reference equality to define functor. We could use the setoid .equals for structural equality

On Fri, Jul 29, 2016, 3:32 PM Jonas Porto notifications@github.com wrote:

I think that Array map method surprisingly doesn't apply as example of Functor

var a = [1, 2 , 3]; a.map(x => x) === a // false

the same for const b = [1, 2, 3]; b.map(x => x) === b // false

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[dead-claudia]

I'll note that Fantasy Land defines equivalence as structural equality, not referential equality.