Chaining Ruby enumerators

I want to connect two Ruby enumerators. Give me all the values from the first, then the second, and so on. Ideally, without forcing any lazy evaluations and flat so I don’t have to think about nested stuff. Like so:

xs = [1, 2, 3].to_enum
ys = [4, 5, 6].to_enum
[xs, ys].chain.to_a # => [1, 2, 3, 4, 5, 6]

I couldn’t figure out how to do that with Ruby’s standard library alone. But, it wasn’t that hard to write my own:

def chain(*enums)
  return to_enum(:chain, *enums) unless block_given?

  enums.each { |enum| enum.each { |e| yield e } }

But it seems like Ruby’s library, Enumerable in particular, is so strong I must have missed something. So, mob programmers, is there a better way to do this? A fancier enumerator-combining thing I’m missing?

I do my best thinking:

  • In the shower. I love to take long showers, and I love my tankless water heater.
  • While talking. Something about my brain is wired directly to my mouth.
  • When I’m not thinking. See also, the value of letting your mind idle, wander, or just walking away from a tricky problem.

Your thinking may vary!

Stored Procedure Modern

The idea behind Facebook’s Relay is to write declarative queries, put them next to the user interaction code that uses them, and compose those queries. It’s a solid idea. But this snippet about Relay Modern made me chuckle:

The teams realized that if the GraphQL queries instead were statically known — that is, they were not altered by runtime conditions — then they could be constructed once during development time and saved on the Facebook servers, and replaced in the mobile app with a tiny identifier. With this approach, the app sends the identifier along with some GraphQL variables, and the Facebook server knows which query to run. No more overhead, massively reduced network traffic, and much faster mobile apps.

Relay Modern adopts a similar approach. The Relay compiler extracts colocated GraphQL snippets from across an app, constructs the necessary queries, saves them on the server ahead of time, and outputs artifacts that the Relay runtime uses to fetch those queries and process their results at runtime.

How many meetings did they need before they renamed this from “GraphQL stored procedures” to “Relay Modern”?

(FWIW, I worked on a system that exposed stored procedures through a web service for client-side interaction code. It wasn’t too bad, setting aside the need to hand write SQL and XSLT.)

We should get back to inventing jetpacks

I don’t like using services like Uber, Twitch, or Favor. I want to like them, because the underlying ideas are pretty futuristic. But the reality of these services is that the new boss wants to squeeze their not-even-employess-anymore just as badly the old boss did. It feels manipulative, like buying a car. Except I’m abetting the manipulation too. :(


The contrast between the gig economy’s rhetoric (everyone is always connecting, having fun, and killing it!) and the conditions that allow it to exist (a lack of dependable employment that pays a living wage) makes this kink in our thinking especially clear.

What happens when the gig economy tries to turn a profit? The race downwards will squeeze out all of their contractors until they can replace them all with automated drivers, commoditized personalities, and punitively-low ad revenue sharing rates. This sounds horribly dystopian but I’m pretty sure it’s already happening. See also: when Google kneecapped bloggers as a side-effect of end-of-lifing Reader and changing Pagerank.

The New York Times, Platform Companies Are Becoming More Powerful — but What Exactly Do They Want?

Platforms are, in a sense, capitalism distilled to its essence. They are proudly experimental and maximally consequential, prone to creating externalities and especially disinclined to address or even acknowledge what happens beyond their rising walls. And accordingly, platforms are the underlying trend that ties together popular narratives about technology and the economy in general. Platforms provide the substructure for the “gig economy” and the “sharing economy”; they’re the economic engine of social media; they’re the architecture of the “attention economy” and the inspiration for claims about the “end of ownership.”

After reading this, I started substituting “platform company” for “company building its own monopoly”. And then it all makes sense. Businesspeople say they love free markets, but give any rational-thinking business the chance and they will create so many “moats” and “barriers to entry” that they resemble tiny state enterprises more than a private business. See also: telecoms and airlines.

Anil Dash, Tech and the Fake Market tactic:

This has been the status quo for most of the last decade. But the next rising wave of tech innovators twist the definition of “market” even further, to a point where they aren’t actually markets at all.

Yes, my confirmation bias is burning. Yes, technologists are doomed to recreate the robber-baron past they didn’t study. Yes, we still have time to change this. Yes, our field needs an ethics refresher. Yes, we should get back to inventing jetpacks!

Jeremy Johnson, It’s time to get a real watch, and an Apple Watch doesn’t count:

…watches are one of the key pieces of jewelry I can sport, and while many have no clue what’s on my wrist, those that do… well do. And they are investments. Usually good purchases will not only last forever (with a little love and care), but go up or retain most of their value over time.

When pal Marcos started talking to me about watches, I realized they checked all the boxes cars do, but at a fraction of the price. If cars check your boxes, look into watches. Jeremy’s intro will get you started without breaking the bank.

Feedback: timing is everything

With feedback, like jokes, timing is everything. Good feedback at a bad time won’t do the trick.

I’ve mostly experienced programming feedback through pull requests. This is way better than no feedback. However, since most pull requests occur at the end of work, and not somewhere in the middle, some kinds of feedback are not conducive to pull requests.

Suppose all feedback falls somewhere on two axes: “timeliness” and “depth”. The narrow sweet spot of code review is apparent:

Pairing and code review are not so similar
Pairing and code review are not so similar

The sweet spot in the top-right corner is when code review works best: unhurried and in-depth feedback. I’d hesitate to call the lower-right corner of hurried, minimal feedback a code review at all; it’s more like rubber stamping.

I’ve often referred to code review, flippantly, as the worst form of pairing yet invented. I’ve given a lot of code review feedback in the past that was better suited to the synchronous nature of pairing than the very asynchronous nature of code reviews. That said, I feel like pairing is an excellent way to give all manners of feedback in the moment the code is being conceived or written. You can immediately point out possible incorrectness or better designs and talk it out, with the code at hand, with your collaborator.

However, we can’t all pair all the time. Let me show you how I’m trying to better time my feedback when I can’t share it immediately.

A tale of four pull requests

Consider four PR subject lines. Which ones are appropriate for architectural ideas? What about optimization ideas? When is deep refactoring feedback appropriate? Can I look at one of these in an hour when I’m done with my current task?

  • “Hotfix Facebook Auth scope”
  • “Prevent sending email for failed payment jobs”
  • “Add tagging to admin storylines listing”
  • “WIP introduce Redis/Lua-based story indexing”

Lately, when I do pull request reviews, I use these guidelines:

  • Figure out if this PR seems like it’s a hot patch to production, a quick fix on existing work, a PR landing new functionality, or a work-in-progress checkpoint seeking feedback.
  • Bear in mind that hot patches and quick fixes are more time sensitive and need yes/no feedback on correctness more than detailed feedback.
  • For hot patches (e.g. “Hotfix FB auth”), I’m only looking for “is this correct” and “will it fix the problem?”; thumbs up or thumbs down and commentary as to what I think is missing to solve the problem. No refactoring ideas. I only touch on performance if I spot a regression.
  • For quick fixes (e.g. “Prevent sending email…”), I’m again looking for correctness and timeliness. I might leave ideas for how to improve the performance or cleanliness of the code later. Those kinds of notes are entirely up to the gumption of the other developer, though. I know the low-gumption feeling of wanting only to fix something and get on to the next thing.
  • Landing new functionality (e.g. “Add tagging…”) receives a full review cycle. Beyond baseline correctness, I’m trying to view this code through my crystal ball. When some value of N is grows, will this code slow down noticeably? Is the code structured so that future changes are easy and obvious?
  • Work-in-progress checkpoints (“WIP introduce Redis/Lua…”) are open to the full spectrum of feedback. Ideas for how to differently structure data, which APIs to export, how to structure objects, how to name the domain model, etc. are all in play. Pretty much the only thing out of play is anything that feels too close to bike shedding.
  • Bear in mind that everyone exists on a spectrum of coding specificity. More seasoned developers are likely open to ideas for restructuring code or considering novel approaches. Less seasoned developers (including seasoned developers new to the team) likely want specific guidance about which changes to make or factors they need to consider.
  • Where I may try to respond to hot patches and quick fixes in less than fifteen minutes, I may wait a couple hours before I look at new functionality or WIP reviews.
  • The most difficult part with these guidelines is how to handle ideas about refactoring on time-sensitive reviews. I want to hold the line against letting lots of little fixes accrete into a medium-sized mess. I don’t want to discourage ideas for refactorings either; I want them separately so I can act on them when I have the energy to really do them.

In short

Use different tactics when sharing feedback for code review; it’s not pairing. Identify patches, reviews, and full feedback pull requests. Sanity check patches, look for correctness in review, look for design in review. Use GitHub’s review process to indicate your feedback is “FYI” vs. “fix this before merging”. Time-to-response is most important for patches and fixes.

Above all: giving feedback is a skill you acquire with practice, empathy, and maintaining a constructive attitude.

Practically applying Clojure

Fourteen Months with Clojure. Dan McKinley on using Clojure to build AWS automation platform Skyliner:

The tricky part isn’t the language so much as it is the slang.

Also, the best and worst part of Clojure:

When the going gets tough, the tough use maps

This is probably better now that specs and schema are popular. Before, when they were mysterious maps full of Very Important State, reading Clojure code (and any kind of Lisp) was pretty challenging.

Make sure you stick around for the joke about covariance and contravariance. Those type theories, hilarious!

Lessons on software complexity from MS Office

I learned a lot of things from Complexity and Strategy by Terry Crowley:

In Fred Brooks’ terms, this was essential complexity, not accidental complexity. Features interact — intentionally — and that makes the cost of implementing the N+1 feature closer to N than 1.

In other words, the ability to change a product is directly proportional to the size of N (features, requirements, spec points, etc.) for the system that express that product. You may find practices that multiply N by 0.9 so you go a little faster. You may back yourself into a corner that multiply N by 1.1 so you go a little slower. But, to borrow again from Fred Brooks, there is no silver bullet. Essential domain complexity is immutable unless you reduce the size of the domain, i.e. cut existing features.

Not even fancy new technologies are correlated with reducing your multiplier, in the long run:

This perspective does cause one to turn a somewhat jaundiced eye towards claims of amazing breakthroughs with new technologies…What I found is that advocates for these new technologies tended to confuse the productivity benefits of working on a small code base (small N essential complexity due to fewer feature interactions and small N cost for features that scale with size of codebase) with the benefits of the new technology itself — efforts using a new technology inherently start small so the benefits get conflated.

Lastly, this is a gem about getting functionality “for free”:

So “free code” tends to be “free as in puppy” rather than “free as in beer”.

All free functionality eventually poops on your rug and chews up your shoes.

Healthcare is a multiplier, not a consumer good

Adam Davidson tells a personal story about a relative who, with health care, could’ve continued his career. Without that healthcare, he ended up addicted and in jail. What the GOP doesn’t get about who pays for health care:

However, dividing health expenditures into these categories misses an important economic reality: health-care spending has a substantial impact on every other sort of economic activity.

Healthcare isn’t consumption, like buying a TV or going to a movie. It is a Keynesian multiplier. Every dollar the government spends on it means an individual or business can spend more than a dollar on something productive in GDP terms.

UPS and FedEx can’t exist without public roads. Southwest and United Airlines can’t exist without the FAA. Lockheed and Northrop can’t exist without the Air Force. Walmart and McDonald’s can’t exist without food stamps. Entrepreneurs find it harder to start without individual access to healthcare.

Yet Republicans are opposed to the existence of all of these. Perhaps business in America relies on more subsidies and government services than Republicans are willing to admit!

Type tinkering

I’m playing with typeful language stuff. Having only done a pinch of Haskell, Scala, and Go tinkering amidst Ruby work over the past ten years, it’s jarring. But, things are much better than they were before I started with Ruby.

Elm in particular is like working with a teammate who is helpful but far more detail oriented than myself. It lets me know when I missed something. It points out cases I overlooked. It’s good software.

I’ve done less with Flow, but I like the idea of incrementally adding types to JavaScript. The type system is pragmatic and makes it easy to introduce types to a program as time and gumption permit. Having a repository of type definitions for popular libraries is a great boon too.

I’m also tinkering with Elixir, which is not really a typed thing. Erlang’s dialyzer is similar in concept to Flow, but different in implementation. Both allow gradually introducing types to systems.

I’m more interested in types stuff for frontends than backends. I want some assurance, in the wild world of browsers and devices, that my systems are soundly structured. Types buy me that. Backends, I feel, benefit from a little more leeway, and are often faster to deploy quick fixes to, such that I can get away without the full rigor of types.

Either way, I’m jazzed about today’s tools that help me think better as I build software.