The one mentioned in the article.

It's not a hack: it's a runtime equivalent that requires that your type implements some interface.

It is a hack. The article lists a whole series of things that are standard in other languages that you can't do in go. Here are some examples:

  Find smallest/largest element in slice
  Find average/standard deviation of slice
  Compute union/intersection of maps
  Find shortest path in node/edge graph
  Apply transformation function to slice/map, returning new slice/map

And here are data structures that other languages have but go does not:

  Sets
  Self-balancing trees, with efficient insertion and traversal in sorted order
  Multimaps, with multiple instances of a key
  Concurrent hash maps, supporting parallel insertions and lookups with no single lock

If it were not a hack, then go would not have these limitations.

> Multimaps, with multiple instances of a key

Isn't this just map[Key][]Value? The standard library uses these in several places, e.g. url.Values and http.Header, with assorted utility functions.

You should send that feedback to the author of the article. I literally just cut and pasted those lists.