allow arrays into the arithmetic macros

[kellyselden]

Closes #341.

cc @mwpastore

[kellyselden]

What should the return value be if the array is empty?

[Fed03]

erroring? What happens if the array contains something that's not a number?

[mwpastore]

That's an interesting question. I think you could probably get away with returning zero, but returning NaN might be more "correct."

[kellyselden]

What happens if the array contains something that's not a number?

@Fed03 It would try to add it 😛

[Fed03]

@Fed03 It would try to add it 😛

In that case, I think that NaN would be the right thing to return when array is empty, like suggested by @mwpastore

[kellyselden]

I ended up saying empty array is zero. I thought it would be easier to reason this:

total: sum('array')

vs

total: or(sum('total'), 0) or total: conditional('total.length', sum('total'), 0)

[kellyselden]

Released in https://github.com/kellyselden/ember-awesome-macros/releases/tag/v0.37.0