> In practice what I see fail most often is not premature optimization but premature abstraction.

Compare and contrast https://people.mpi-sws.org/~dreyer/tor/papers/wadler.pdf

Really need that [flag bot] button added to HN.

You tend to see it a lot in "Enterprise" software (.Net and Java shops in particular). A lot of Enterprise Software Architects will reach for their favored abstractions out of practice as opposed to if they fit. Custom solution providers will build a bunch of the same out of practice.

This is something I tend to consider far, far worse than "AI Slop" in practice. I always hated Microsoft Enterprise Library's Data Access Application Block (DAAB) in practice. I've literally only ever seen one product that supported multiple database backends that necessitated that level of abstraction... but I've seen that library well over a dozen times in practice. Just as a specific example.

IMO, abstractions should generally serve to make the rest of the codebase reasonable more often than not... abstractions that hide complexity are useful... abstractions that add complexity much less so.

It's easy to see this outside of the perspective of a solo game developer. We all have deadlines to manage even in the regular 'corporate world'. And engineering time spent on a problem also translates to an actual cost.

It's a good consideration tbh.

Agreed, in my experience, rule 5 should be rule 1. I think I also heard it said (paraphrased) as "show we your code and I'll be forever confused, show me your database schema and everything will become obvious".

Having implemented my shared of highly complex high-performance algorithms in the past, the key was always to figure out how to massage the raw data into structures that allow the algorithm to fly. It requires both a decent knowledge of the various algorithm options you have, as well as being flexible to see that the data could be presented a different way to get to the same result orders of magnitude faster.

> refinement of the data structures (and the APIs they expose / are associated with)

I think rule 5 is often ignored by a lot of distributed services. Where you have to make several calls, each with their own http, db and "security" overhead, when one would do. Then these each end up with caching layers because they are "slow" (in aggregate).

I feel like every time I have expected an area to be the major bottleneck it has been. Sometimes some areas perform worse than I expected, usually something that hasn't been coded well, but generally its pretty easy to spot the computationally heavy or many remote call areas well before you program them.

I have several times done performance tests before starting a project to confirm it can be made fast enough to be viable, the entire approach can often shift depending on how quickly something can be done.

> you can kinda tell where you should optimize ahead of time

Rules are "kinda" made to be broken. Be free.

I've been sticking to these rules (and will keep sticking to them) for as long as I can program (I've been doing it for the last 30 years).

IMHO, you can feel that a bottleneck is likely to occur, but you definitely can't tell where, when, or how it will actually happen.

ROFL, I wish Pike had known what he was talking about. /s ;)

Rob Pike wrote Unix and Golang, but sure, you’re built different.

Huh, I've always understood that quote very differently, with emphasis on "premature" ... not as in, "don't optimize" but more as in "don't optimize before you've understood the problem" ... or, as a CS professor of mine said "Make it work first, THEN make it work fast" ...

Another one from my personal experience: apply DRY principles (don't repeat yourself) the third time you need something. Or in other words: you're allowed to copy-and-paste the same piece of code in two different places.

Far too often we generalise a piece of logic that we need in one or two places, making things more complicated for ourselves whenever they inevitably start to differ. And chances are very slim we will actually need it more than twice.

Premature generalisation is the most common mistake that separates a junior developer from an experienced one.

> and the missing context is essential.

Oh yes, I'd recommend everyone who uses the phrase reads the rest of the paper to see the kinds of optimisations that Knuth considers justified. For example, optimising memory accesses in quicksort.

I wish we lived in a world where quotes could be that powerful. But I'm afraid in reality this quote, like any other, is just used as a justification after the fact.

Actually, I do not believe devs are to blame, or that CS education is to blame; I believe that's an unfortunate law of society that complexity piles up faster than we can manage it. Of course the economic system rewards shiping today at the expense of tomorrow's maintenance, and also rewards splitting systems in seemingly independent subsystems that are simpler in isolation but results in a more complex machinery (cloud, microservices...)

I'm even wondering if it's not a more fundamental law than that, because adding complexity is always simpler than removing it, right? Kind of a second law of termodynamic for code.

I was a bit worried you are paraphrasing Rob Pike, but no, he actually agrees with that Knuth quote.

I am almost certain that people building bloated software are not willfully misunderstanding this quote; it's likely they never heard about it. Let's not ignore the relevance of this half a century old advice just because many programmers do not care about efficiency or do not understand how computers work. Premature optimization is exactly that, the fact that is premature makes it wrong, regardless if it's about GOTO statements in the 70s or a some modern equivalent where in the name of craft or fun people make their apps a lot more complex than they should be. I wouldn't be surprised if some of the brutally inefficient code you mention was so because people optimized prematurely for web-scale and their app never ever needed those abstractions and extra components. The advice applies both to hackers doing micro-optimizations and architecture astronauts dreaming too big IMHO.

Ignoring optimization opportunities until you see the profile only works when you actually profile!

Profiling never achieved its place in most developers’ core loop the way that compiling, linting, or unit testing did.

How many real CI/CD pipelines spit out flame graphs alongside test results?

I don't think the quote itself is responsible for any of that.

It's true that premature optimization (that is, optimization before you've measured the software and determined whether the optimization is going to make any real-world difference) is bad.

The reality, though, is that most programmers aren't grappling with whether their optimizations are premature, they're grappling with whether to optimize at all. At most companies, once the code works, it ships. There's little, if any, time given for an extra "optimization" pass.

It's only after customers start complaining about performance (or higher-ups start complaining about compute costs) that programmers are given any time to go through and optimize things. By which point refactoring the code is now much harder than it wouldn've been originally.

This discussion kind of irks me. I just read these posts as: "The quote saying A is bad. Actually it said A all along!"

It's just complaining about others making a different value judgement for what is a worthwhile optimization. Hiding behind the 'true meaning of the quote' is pointless.

> From his 1974 paper, "Structured Programming with go to Statements":

> He was talking about using GOTO statements in C.

I don’t think he was talking about C. That paper is from December 1974, and (early) C is from 1972, and “The UNIX Time-Sharing System” (https://dsf.berkeley.edu/cs262/unix.pdf) is from July 1974, so time wise, he could have known C, but AFAICT that paper doesn’t mention C, and the examples are PL/I or (what to me looks like) pseudocode, using ‘:=’ for assignment, ‘if…fi’ and ‘while…repeat’ for block, ‘go to’ and not C’s ‘goto’, etc.

Totally agree. I’ve see that quote used to justify wilfully ignoring basic performance techniques. Then people are surprised when the app is creaking exactly due to the lack of care taken earlier. I would tend to argue the other way most of the time: a little performance consideration goes a long way!

Maybe I’ve had an unrepresentative career, but I’ve never worked anywhere where there’s much time to fiddle with performance optimisations, let alone those that make the code/system significantly harder to understand. I expect that’s true of most people working in mainstream tech companies of the last twenty years or so. And so that quote is basically never applicable.

I agree. Faster hardware or horizontal scaling on distributed cloud environments can mask the problem; but it certainly doesn't solve the problem of bloated, inefficient software.

While it might not be necessary to spend hours fine-tuning every function; code optimization should be the mindset of every programmer no matter what they are coding.

How many fewer data centers would we need if all that software running in them was more efficient?

https://didgets.substack.com/p/finding-and-fixing-a-billion-...

Slow code is more of a project management problem. Features are important and visible on the roadmap. Performance usually isn't until it hits "unacceptable", which may take a while to feed back. That's all it is.

(AI will probably make this worse as well, having a bloat tendency all of its own)

> generations of programmers have now been raised to believe that brutally inefficient, bloated, and slow software is just fine.

I believe people don't think about Knuth when they choose to write app in Electron. Some other forces might be at play here.

A lot of developers get enamored by fetishes. Just one example, because it's one i always struggle to vanquish in any of my teams.

Devs are obsessed with introducing functional-style constructs everywhere, just for the sake of it. FP is great for some classes of software, but baseline crufty for anything that requires responsiveness (front-ends basically), let alone anything at real interactive speeds (games, geo-software, ...)

The "premature optimization" quote is then always used as a way to ignore that entire code paths will be spamming the heap with hundreds of thousands of temporary junk, useless lexical scopes, and so forth. Writing it lean the first time is never considered, because of adherence to these fetishes (mutability is bad, oo is bad, loops lead to off-by-one errors, ...). It's absolutely exhausting to have these conversations, it's always starting from the ground up and these quotes like "premature optimization is the root of all evil" are only used as invocations to ward of criticism.

Picking the starting point is very important. "optimization" is the process of going from that starting point to a more performant point.

If you don't know enough to pick good starting points you probably won't know enough to optimize well. So don't optimize prematurely.

If you are experienced enough to pick good starting points, still don't optimize prematurely.

If you see a bad starting point picked by someone else, by all means, point it out if it will be problematic now or in the foreseeable future, because that's a bug.

> Multiple generations of programmers have now been raised to believe that brutally inefficient, bloated, and slow software is just fine

100%

Don't confuse premature pessimization for the warnings against premature optimization.

I can write bubble sort, it is simple and I have confidence it will work. I wrote quicksort for class once - I turned in something that mostly worked but there were bugs I couldn't fix in time (but I could if I spent more time - I think...)

However writing bubble sort is wrong because any good language has a sort in the standard library (likely timsort or something else than quicksort in the real world)

I hear you, friend!

While you were seeing those problems with Java at Google, I saw seeing it with Python.

So many levels of indirection. Holy cow! So many unneeded superclasses and mixins! You can’t reason about code if the indirection is deeper than the human mind can grasp.

There was also a belief that list comprehensions were magically better somehow and would expand to 10-line monstrosities of unreadable code when a nested for loop would have been more readable and just as fast but because list comprehensions were fetishized nobody would stop at their natural readability limits. The result was like reading the run-on sentence you just suffered through.

Anyone else feel like bloat is usually not an algorithmic problem, but rather a library or environment issue most of the time?

As someone currently writing 16-18 tables all with common definition, and crud, Id like some abstraction

I think the bigger problem is that "Premature optimization is the root of all evil" is a statement made by software engineers to feel more comfortable in their shortcomings.

That's not to bemoan the engineer with shortcomings. Even the most experienced and educated engineer might find themself outside their comfort zone, implementing code without the ability to anticipate the performance characteristics under the hood. A mental model of computation can only go so far.

Articulated more succinctly, one might say "Use the profiler, and use it often."

At least before the LLM world you would have to trade money (aka more compute) for time to market. What is the point of spending a single second optimizing a query when your database has 10 users?

Of course today this has changed. You can have multiple agents working on micro optimizing everything and have the pie and eat it too.

Totally agree. Out of this context, the word "premature" can mean too many things.

I always point out the operational word is "premature".

This is the sort of pontifical statement that old guys like me tend to make which is strictly wrong but also contains a lot of wisdom.

Yes, software is bloated, full of useless abstractions and bad design. You kids(well, anyone programming post 1980, so myself included) should be ashamed. Also let's not forget that those abstractions helped us solve problems and our friends in silicon valley(ok that no longer makes sense but imagine if SillyValley still just made HW) covered our mistakes. But yeah, we write crap a lot of the time.

But as other folks have said, it doesn't mean "don't optimize."

I've always used my own version of the phrase, which is: "Don't be stupid." As in, don't do dumb, expensive things unless you need to for a prototype. Don't start with a design that is far from optimal and slow. After profiling, fix the slow things. I'm pretty sure that's what most folks do on some level.

> Multiple generations of programmers have now been raised to believe that brutally inefficient, bloated, and slow software is just fine. There is no limit to the amount of boilerplate and indirection a computer can be forced to execute. There is no ceiling to the crystalline abstractions emerging from these geniuses. There is no amount of time too long for a JVM to spend starting.

I think that's due to people doing premature optimization! If people took the quote to heart, they would be less inclined to increasing the amount of boilerplate and indirection.

So you're saying people have misunderstood "premature optimisation is the root of all evil" as "optimisation is the root of all evil"?

I don't think you can blame this phrase if people are going to drop an entire word out of an eight word sentence. The very first word, no less.

I too learned this the hard way, via a supposedly concurrent priority queue that did quadratic-time work while holding a lock over the entire thing. I was told that "premature optimization is the root of all evil."

Sorry, folks, but that's just an excuse to make dumb choices. Premature _micro_optimization is the root of all evil.

EDIT: It was great training for when I started working on browser performance, though!

In all honesty, this is one of the less abused quotes, and I have seen more benefit from it than harm.

Like you, I've seen people produce a lot of slow code, but it's mostly been from people who would have a really hard time writing faster code that's less wrong.

I hate slow software, but I'd pick it anytime over bogus software. Also, generally, it's easier to fix performance problems than incorrect behavior, especially so when the error has created data that's stored somewhere we might not have access to. But even more so, when the harm has reached the real world.

> I have lived the absolute nightmares that evolve from the willful misunderstanding of this quote.

how do you know which code was written using this quote in mind.

It has less to do with a quote and more to do with CS education (and the market) rewarding minimal functionality over performance, security, fault-tolerance, etc.

The average university CS student in USA (and India I presume) is taught to "hack it" at any cost, and we see the results.

> I have lived the absolute nightmares that evolve from the willful misunderstanding of this quote.

Then the quote wasn’t the problem. The wilful misunderstanding was the problem.

> but I think his versions are better, they deserve to be presented by themselves, instead of alongside the mental clickbait of the classic aphorisms

keeping the historical chain of thinking alive is good, actually

> If you can't tell in advance what is performance critical, then consider everything to be performance critical.

As for rule 2: first you measure.

Yeah, but I doubt many of the newer generation are going to read this. I manage a team of engineers, and one of the recent-ish graduates asked me in our 1-on-1 if it's still worth learning Python given that he can just write prompts. (Python is the language all our tools use).

If the next generation doesn't even want to learn a programming language, they're definitely not going to learn how to write _clean_ code.

Maybe I'm just overly pessimistic about junior engineers at the moment because of that conversation lol.

Syntactic sugar is cancer of the semicolon.

That's Rule 5 no?

There's also:

>I will, in fact, claim that the difference between a bad programmer and a good one is whether he considers his code or his data structures more important. Bad programmers worry about the code. Good programmers worry about data structures and their relationships.

-- Linus Torvalds

I believe the actual quote is:

"Show me your flowchart and conceal your tables, and I shall continue to be mystified. Show me your tables, and I won't usually need your flowchart; it'll be obvious." -- Fred Brooks, The Mythical Man Month (1975)

As I'm sure more and more people are using AI to document old systems, even just to get a foothold in them personally if they don't intend to share it, here's a hint related to that: By default, if you fire an AI at a programming base, at least in my experience you get the usual documentation you expect from a system: This is the list of "key modules", this module does this, this module does that, this module does the other thing.

This is the worst sort of documentation; technically true but quite unenlightening. It is, in the parlance of the Fred Brooks quote mentioned in a sibling comment, neither the "flowchart" nor the "tables"; it is simply a brute enumeration of code.

To which the fix is, ask for the right thing. Ask for it to analyze the key data structures (tables) and provide you the flow through the program (the flowchart). It'll do it no problem. Might be inaccurate, as is a hazard with all documentation, but it makes as good a try at this style of documentation as "conventional" documentation.

Honestly one of the biggest problems I have with AI coding and documentation is just that the training set is filled to the brim with mediocrity and the defaults are inferior like this on numerous fronts. Also relevant to this conversation is that AI tends to code the same way it documents and it won't have either clear flow charts or tables unless you carefully prompt for them. It's pretty good at doing it when you ask, but if you don't ask you're gonna get a mess.

(And I find, at least in my contexts, using opus, you can't seem to prompt it to "use good data structures" in advance, it just writes scripting code like it always does and like that part of the prompt wasn't there. You pretty much have to come back in after its first cut and tell it what data structures to create. Then it's really good at the rest. YMMV, as is the way of AI.)

I find languages like Haskell, ReScript/OCaml to work really well for CRUD applications because they push you to think about your data and types first. Then you think about the transformations you want to make on the data via functions. When looking at new code I usually look for the types first, specifically what is getting stored and read.

Reminded me of this thread between Alan Kay and Rich Hickey where Alan Kay thinks "data" is a bad idea.

My interpretation of his point of view is that what you need is a process/interpreter/live object that 'explains' the data.

https://news.ycombinator.com/item?id=11945722

EDIT: He writes more about it in Quora. In brief, he says it is 'meaning', not 'data' that is central to programming.

https://qr.ae/pCVB9m

Aren't they basically saying opposite things? Perlis is saying "don't choose the right data structure, shoehorn your data into the most popular one". This advice might have made sense before generic programming was widespread; I think it's obsolete.

This quote from “Dive into Python” when I was a fresh graduate was one of the most impacting lines I ever read in a programming book.

> Busywork code is not important. Data is important. And data is not difficult. It's only data. If you have too much, filter it. If it's not what you want, map it. Focus on the data; leave the busywork behind.

> Rule 5. Data dominates. If you've chosen the right data structures and organized things well, the algorithms will almost always be self-evident. Data structures, not algorithms, are central to programming.

If I have learned one thing in my 30-40 years spent writing code, it is this.

But doesn't No. 2 directly conflict with Pike's 5th rule? It seems to me these are all aphorisms that have to be taken with a grain of salt.

> 2. Functions delay binding; data structures induce binding. Moral: Structure data late in the programming process.

Nice to see Perlis mentioned once in a while. Reading SICP again, still learning new things.

I feel like these are far more vague and less actionable than the 5 Pike rules.

With 100 functions and one datastructure it is almost as programming with a global variables where new instance is equivalent to a new process. Doesn’t seem like a good rule to follow.

As much as relational DBs have held back enterprise software for a very long time by being so conservative in their development, the fact that they force you to put this relationship absolutely front-of-mind is excellent.

" 9. It is better to have 100 functions operate on one data structure than 10 functions on 10 data structures."

That's great

Was the "J" short for "Cassandra"?

    When someone says "I want a programming language in which I need only say what I wish done," give him a lollipop.

Also basically everything DHH ever said (I stopped using Rails 15 years ago but just defining data relationships in YAML and typing a single command to get a functioning website and database was in fact pretty cool in the oughts).

Perlis is just wrong in that way academics so often are.

Pike is right.

… if the data structures are crap.

Good software can handle crap data.

If Dijkstra blamed Knuth it would have been the best recursive joke ever.

I've always thought it was Dijkstra - it even sounds Dijkstra-ish.

> Even knowing with 100% certainty that performance will be subpar

I think there is value in attempting to do something the "wrong way" on purpose to some extent. I have walked into many situations where I was beyond convinced that the performance of something would suck only to be corrected harshly by the realities of modern computer systems.

Framing things as "yes, I know the performance is definitely not ideal in this iteration" puts that monkey in a proper cage until the next time around. If you don't frame it this way up front, you might be constantly baited into chasing the performance monkey around. Its taunts can be really difficult to ignore.

How good is your model at picking good data structures?

There’s several orders of magnitude less available discussion of selecting data structures for problem domains than there is code.

If the underlying information is implicit in high volume of code available then maybe the models are good at it, especially when driven by devs who can/will prompt in that direction. And that assumption seems likely related to how much code was written by devs who focus on data.

Would be cool to see the live reaction of Rob Pike to this comment

Unironically. Every time I asked a LLM to make something faster, they always tried blind code optimisations, rather than measure.

Potentially its by either (or even both independently). Knuth originally attributed it to Hoare, but there's no paper trail to demonstrate Hoare actually coined it first

Because people only quote it partially.

> We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%.

When you explore a problem, use Python and lists/sets/dictionaries/JSON. Wait with types and specific data structures till you have understanding. Speed of development over speed of execution.

When you know what and how to build commit to good data structures. Do the types, structs, classes, Trie, CRDTs, XML, Protobuf, Parquet and whatnot where apropriate. Instrument your program. The efficiency of the final product counts.

Afaict Perlis is more saying not to expose data layout in the boundaries between abstractions, rather to keep them pure and functional.

So not really a contradiction, just Perlis talking about the functional shell and Torvalds/Pike talking about the imperative core.

That is indeed contradictory and what those things say.

Good structure comes from exploring until you understand the problem well AND THEN letting data structure dominate.

KISS

Yes, and I'd say it's more true now than then. Best case, your fancy algorithms are super-sizing code that runs 1% of the time, always kicking more-often-run code out of the most critical CPU caches. Worst case, your fancy algorithms contain security bugs, and the bad guys cash in.

I think for people starting out - rule 5 isn't perhaps that obvious.

> Rule 5. Data dominates. If you've chosen the right data structures and organized things well, the algorithms will almost always be self-evident. Data structures, not algorithms, are central to programming.

If want to solve a problem - it's natural to think about logic flow and the code that implements that first and the data structures are an after thought, whereas Rule 5 is spot on.

Conputers are machines that transform an input to an output.

A good chunk of great advice is obvious things that people still fail to do.

That's why a collection of "obvious" things formulated in a convincing way by a person with big street cred is still useful and worth elevating.

Can't be but so obvious if the first comment I saw here was that the first two rules didn't seem so important. =)

Definitely not obvious to everybody.

You've got to elevate some obviously correct things, otherwise social media will fill the void with nonobviously incorrect things.

I'd call it more derivative than obvious.

"Why quote someone who's just quoting someone else?" — Michael Scott — knorker