[songgao]

This old blog post has a pretty good explanation about how Go slice works: https://blog.golang.org/go-slices-usage-and-internals

Once you realize slices are just (pointer, length, capacity) structures, and the structure itself is copied by value, the first 2 WAT is pretty trivial.

[erik_seaberg]

It's kind of broken that slices are immutable but maps aren't, and that reading a slice can panic but reading a map can't.

[SamWhited]

Reading from a nil slice and map feel consistent to me. If you read from a nil map you get the same result as reading a key that is not in a non-nil map (because that key is clearly not in the map because it's nil). Similarly, if you read from a nil slice you get the same result as reading an index that's not in the slice, an out of bounds access.

[lifthrasiir]

Trivial in isolation, but it is much harder to see the problem in a heap of source code. In general such "surprise moments" should be regarded seriously however it seems trivial in isolation.