foo = [3,4,5];
get(foo,null) => 3
foo:0 == foo:null => true
delete(foo:null); foo => [4,5]

foo = [1];
has(foo,null) => true
foo = [];
has(foo,null) => false

Bug or working as intended? I ask mostly because it isn't mentioned in the docs and it messes up deleting specific entries as seen below

bar = ['a','b','c']
delete(bar,bar~'a'); bar => ['b','c']
// a isn't in the list, so index returns null, delete is still happy to nuke entry at index 0 though
delete(bar,bar~'a'); bar => ['c']

It is definitely intended for null to act as zero for most stuff, and I'd assume this to be too given it's caused directly by that, though I'm not sure.

good point. My first gut feeling is that null should be considered 0 in math, but not so much logic and that proves this principle