Miss Dada  🏳️‍⚧️

also I never actually want arbitrary flattening - if my data is arbitrarily deep, I want an interpreter or visitor - if my data is one level deep, I want flatMap - if I don't know how deep it is, I have a design problem

I'm with you that flatten should always be `flatMap(id)`. FWIW, `Array.prototype.flat` lets you pass a depth, but it defaults to 1 so other than the hole thing it is identical to `flatMap(id)`

Have you seen how an array’s length property is defined? https://www.ecma-international.org/ecma-262/5.1/#sec-15.4 … tl;dr it looks at properties on the object, determines which are array indexes, adds one to the largest, and bam, length.

> object has a length property whose value is always a nonnegative integer I'm pretty sure this is for a different language

I mean, it’s a Number but it can also be a non-negative integer

"The language spec has the concept of integers you just don't get to use them"

I mean parseInt is there