Add a recipie for checking if an object is empty

[adamchester]

It took me quite a while to figure out how to conditionally check if the rest(true) object was empty, so here it is:

[SimonCropp]

@adamchester is there an existing test for that scenario?

[nblumhardt]

@SimonCropp I think for these the tests usually cover the individual functions and operators; the recipes are just examples. Or did I misunderstand what you mean? Cheers!

[adamchester]

Yeah I think it’s a good call to consider if there’s a test that covers this issue.

documenting it is taking it from an accident to a thing we want to keep working?

[nblumhardt]

👍

Not an accident though - just regular structural equality at work :-)

Should be nice and easy to add some to expression-cases.asv if anyone's keen! I'm on the road so won't be able to loop back for a little while :-)

[adamchester-lmg]

I found this test case:

{rest(true)}                                         ⇶ {}

I wonder if that's enough?

[nblumhardt]

I think so 👍 -- that's the same logic