Golang Diaries II

I still haven’t written a thousand lines of Go; but what I have created does useful work and (considering I had to learn a language and a bunch of libraries along the way) didn’t burn that much time. Herewith another batch of programming-permanoob reportage.

Previously: Golang Diaries I.

Illustrated Love Letter · I’m a Web guy, and this speaks for itself:

  resp, err := http.Get(uri)

  if err != nil {
    // horrible networking error, deal
    return failure
  }
  if resp.StatusCode != 200 {
    // grouchy server, deal
    return failure
  }
  mediaType := resp.Header.Get("Content-Type")
  if !strings.HasPrefix(mediaType, "application/json") {
    // bogus media type, deal
    return failure
  }

  defer resp.Body.Close()
  body, err := ioutil.ReadAll(resp.Body)
  // body is a byte array with the server response

Isn’t it pathetic that so many allegedly-mainstream languages don’t have HTTP libraries that are this natural and idiomatic?

Other Good Stuff · Just like everyone says, Go makes concurrency a lot easier, without having to think about monads or actors or transactions. Just write simple linear code (like that HTTP stuff above) and farm it out with go-routines and channels.

Here’s sort of the core app logic in findIDP:

  c := make(chan SearchResult)
  go timeout(c)
  go searchDNS(email, c, logger)
  go searchWebfinger(email, c, logger)
  go searchWebFist(email, c, logger)
  go matchDomainPatterns(email, c, logger)

This is great... these all go do their thing and send the results back whenever they get them (the WebFist flow involves two different HTTP round-trips). Then I watch the results trickle in, bail on a time-out (currently 2 seconds, hmm), exit if I get an authoritative result, otherwise select from among the others based on a bunch of heuristics; I don’t spend a microsecond thinking about concurrency issues.

Some of the important virtues of Erlang here, without the dorky syntax and general weirdness.

Happiness · Matz wrote Ruby to make programmers happy, and it makes me happy. Go doesn’t particularly, but I’ll probably keep using it.

In Ruby code I find the smallest semantic gap between the image of the problem in my head and the code on my screen. In C, I find the smallest semantic gap between the code on the screen and my understanding of what the computer does.

Go gets real close to C in terms of the mapping onto the underlying machine. There’s no reason that Go shouldn’t be as fast as C, and given the quality of the team working on it, I’m sure it will be.

Go isn’t nearly as close as Ruby to the model in my head, but it’s a whole hell of a lot closer than C is. This seems to me like a decent trade-off.

I stumbled across Quotes About Go Programming at cat-v.org, and while the enthusiasts are kind of boring, I found I was resonating with some of the more balanced takes, such as If I had to describe Go with one word it’d be “sensible”. and Why would you have a language that is not theoretically exciting? Because it’s very useful.

Type -= Ceremony · Static typing is so much less painful when you have good type inference, as Go has. I’m wondering how much of my cursing at Java is really at all the declaration ceremony; it gets in the way of the work I’m trying to do. Sometimes it’s helpful for readability to make a type visible, and Go has the var facility for doing that.

And Last, the Gripes · It really irritates me, that in a modern programming language, if I have an array full of type Foo, and a function that converts Foo to Bar, there isn’t a map() method that just gives me an array full of Bar. And then a separate concurrentMap(), which does the obvious.

Golang is sort of half-pregnant; it provides the incredibly-useful append() method, that appends to any type of array.

No, this is not a plea for generics! I just want some functional goodies.

Speaking of missing goodies, a little introspection would be nice. If you glance at that findIDP code fragment above, it’s obvious that I have a lot of different chunks of software that offer what you might call a Searcher interface. Why can’t I have them all in a directory or package or somewhere and let the program figure out how many there are and fire them all off? Quite possibly it can and I just haven’t got there yet.

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