1. Like read(2), io.Reader.Read takes a slice parameter to which it writes, it doesn't return one. This is better for a "legitimate" read stream as the caller c

1. Like read(2), io.Reader.Read takes a slice parameter to which it writes, it doesn't return one. This is better for a "legitimate" read stream as the caller can amortise allocations. 2. And Read takes the slice by value, so the length, capacity, and buffer pointer are copied into the callee. This gives no way of "swapping buffers", even ignoring that the caller may have issues getting back a slice with a completely different size and capacity than they sent / expected.