In my particular example, these were of course deliberately simple snippets to illustrate the point. The power comes in chaining these things, .map.filter.reduce... . Using iteration, you end up writing a lot of boilerplate that is much harder to parallelise, and extremely difficult to lazily evaluate. Without these constructs, to express "the concept of filtering & reducing an array", the reader of your program needs to read how you implemented those things, in addition to what you're using them for. You can do that stuff yourself in goroutines, but there is no contest to having native support for these extremely common operations.