I grant you that the API for capacity and length when creating a slice in Go is bad because of this exact mistake, and I believe a few of the Go authors said th

I grant you that the API for capacity and length when creating a slice in Go is bad because of this exact mistake, and I believe a few of the Go authors said they regretted it and would like to change it. However, it's odd to classify this as an advantage of Ruby, because pre-allocating memory for a large slice like this has been one of the biggest single performance advantages when we moved from Python to Go, and it's effectively a one line change. For known-to-be-tiny slices we don't even bother.