I'd have to agree, that would fit my programming style, however it's not unreasonable for a beginner to think of slices and interfaces as basically "A pointer w

I'd have to agree, that would fit my programming style, however it's not unreasonable for a beginner to think of slices and interfaces as basically "A pointer with some additional info". So if you have two data-structures that have a slice of the same data, you may conceptualize that as two data-structures pointing to the same data. It's wrong, but it's also not far off. I do think it's a little surprising that this doesn't work: func append6(is []int){ append(is, 6); } even though it appears to with basic testing.