[ThrowawayR2]

Personally, I've always thought this letter was the plainest proof that Dijkstra's pithy quotes (and those that parrot them) should not be taken seriously, no matter how entertaining they are. That list covers most the major languages of the day; what he would have to say about $(YOUR_FAVORITE_LANGUAGE) would surely be equally unkind were he alive today.

That isn't to say that he did not have valid reasoning for his dislikes as a language expert and a mathematician but those reasons are not ones the bulk of practitioners would likely agree are valid.

[dkarl]

Everything Dijkstra says makes sense if you believe that computing cannot scale without correctness. He was wrong about that one thing, and to be fair to him, it's still a little amazing in retrospect, even when we can look back over the decades of history through which we've created a society dependent on vast, unimaginably complex, world-spanning computing systems built out of pieces that are virtually all broken.

And it's not like he was a lone crank railing against the 99% who were moving forward with a well-founded idea of how computing could scale indefinitely by composing incorrect programs. Just like today, 99% of programming, including programming for government programs and vital infrastructure, was done by people who were only hoping to make their own projects succeed well enough for the next six months to three years. I'm sure there were brilliant people who made intelligent arguments against the need for correctness, but their arguments didn't carry the day. Complacency and short-term thinking did.

In that context, Dijkstra's pessimism and his use of harsh, attention-getting language makes a lot of sense. How many people at the time really understood that in 2020 every part of our civilization would depend on code compiled by compilers with bugs, linked with libraries with bugs, in virtual machines with bugs, on operating systems with bugs, on CPUs with bugs in their microcode, and yet it would still all mostly work?

[munificent]

> if you believe that computing cannot scale without correctness. He was wrong about that one thing, and to be fair to him, it's still a little amazing in retrospect,

That is clearly wrong if one is willing to take a moment to stop gazing at the wonder of pure mathematics and look at the outside world. There is no notion of "correctness" for the pyramids of Egypt, the dykes of the Netherlands, Milan Cathedral, or the world economy and yet those huge-scale systems all function.

> Dijkstra's pessimism and his use of harsh, attention-getting language makes a lot of sense.

It makes sense in terms of Dijkstra's personality, but it makes no logical sense. If you believe mathematical correctness is such a valuable principle, then you should be able to leverage that same principle in one's own arguments. The fact that Dijkstra couldn't dispassionately prove that correctness was vital and had to resort to emotionally-loaded weasel words undermines his own claim.

[ThenAsNow]

> That is clearly wrong if one is willing to take a moment to stop gazing at the wonder of pure mathematics and look at the outside world. There is no notion of "correctness" for the pyramids of Egypt, the dykes of the Netherlands, Milan Cathedral, or the world economy and yet those huge-scale systems all function.

Wow, couldn't disagree with this more, at least on your examples of civil engineering (buildings, dikes). There are testable, comprehensive physical principles that govern whether any of these engineered products function in their most fundamentally-intended ways. This is the reason most buildings are resilient and don't collapse under load, or that dams keep water from flowing uncontrolled. You can debate "correctness" in the sense of the purpose the product serves, but there is the principle of correctness of construction which your civil engineering examples (and anything truly engineered) satisfy. Correctness in construction is not subjective.

[raiph]

> Correctness in construction is not subjective.

Perhaps, but it's never certain. So things that are "correct" can still be wrong.

Here's how Einstein expressed his disagreement with what you are saying:

> As far as the laws of mathematics are certain, they do not refer to reality, and as far as they refer to reality, they are not certain.

Nothing in physics (or any other science) is certain. All one can do in science (other than mathematics) is disprove. One cannot prove.

To prove you would have to be all knowing. You would have to have taken into account all relevant aspects of all physical characteristics. For example, all known aspects of quantum mechanics, including the uncertainty principle, AND all relevant unknown aspects of quantum mechanics, which is guaranteed to be hit and miss, and can rationally be expected to contain an unknown number of misses that isn't zero.

It's the human propensity to ignore these fundamentals that leads to things like the Tacoma Bridge collapse.[0]

[0] https://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)

[munificent]

> There are testable, comprehensive physical principles that govern whether any of these engineered products function in their most fundamentally-intended ways.

These are statistical engineering tests of the probability of failure under certain conditions. That is not at all what Dijkstra would consider to be "correctness". Dijkstra is talking about mathematical proof. In mathematics, one does not say "1 + 2 = 3 plus or minus 0.1 with a safety factor of 2".

[ThenAsNow]

When we determine if an aircraft trims, or a boat floats, it is not correct to say it is statistical engineering test of the probability of failure. You formalize the properties the system must have in order to not fail, and you use conservation equations to ultimately compute whether or not the system satisfies those properties. Margins are used to account for parameters that have uncertainty attached. All of these elements are subject to symbolic mathematical formalism. One can quite clearly state the inequalities that must be satisfied to be, e.g., controllable.

It's unclear how this would be any different than mathematically formalizing a distributed system, identifying the properties that constitute correctness of operation of that distributed system, and symbolically proving that subject to certain assumptions, the distributed system model does or does not satisfy those properties. This would presumably be consistent with the Dijkstra view of mathematical correctness.

[dkarl]

> There is no notion of "correctness" for the pyramids of Egypt, the dykes of the Netherlands, Milan Cathedral, or the world economy and yet those huge-scale systems all function.

I think it's impossible to come up with a rational judgment of whether the world economy "functions." I mean, those of us who are alive are alive, but there are a lot of things that have happened that haven't been ideal.

Besides the world economy, nothing you mention has the functional complexity of a large piece of software, and none of it was designed and built with much confidence, other than confidence that came from similarity to previous designs, and from an optimistic outlook that issues encountered during construction could be coped with. This wall is cracking, so we tear it down and rebuild it a little thicker. We have a few centuries, after all. I think you're right that modern software projects are analogous to ancient pyramids and medieval cathedrals. That's pretty much where we are. Yet somehow, working at that low level of sophistication, we've built working software that is orders of magnitude more complex than cathedrals.

I'm not saying I know how to improve on the situation, or even that we can; I'm just pointing out how different it is from, say, contemporary structural engineering where we can analyze the design of a novel structure and have a pretty good idea of whether it will be safe based on its geometry and known characteristics of materials and how they're joined. It's amazing that we've reached the scale we have with nothing comparable.

> If you believe mathematical correctness is such a valuable principle, then you should be able to leverage that same principle in one's own arguments.

The idea that mathematical reasoning is on some spectrum with dispassionate discourse has motivated hundreds of years of attempts to improve natural language by making it more mathematical. Result: some interesting contributions to philosophy but very little change in how people communicate. People are still people.

[watwut]

Imo, the real issue is that people seem to think that smart mathematicians or scientists don't argue like normal people, don't get emotional when arguing and always talk from divine truth.

The issue have nothing to do with mathematical correctness, so you can't apply the same principles. This is not math. But, Dijkstra's it's not being logical in arguments, because he is not of dick and likely this style of arguing was working for him in his life.

[galaxyLogic]

Good points. I think a way of looking at it is that much of software development we do today is about communication, not engineering. Think of web-sites they are all about communicating something. And in a sense when you write a program you do so to communicate with the computer.

Of course there are critical software engineering projects as well, Boeing MAX comes to mind.

[madhadron]

The context of this EWD is somewhat lost to history, because Dijkstra's point of view in many cases won so thoroughly that we cannot conceive of what he was describing.

The BASIC he is describing had no call stack, nothing that would resemble a function in today's languages. FORTRAN at the time handed masses of state around in global variables and the latest version had just added subroutines and functions. This is after ALGOL 60 had established the model that we all take for granted today.

I think the bulk of practitioners today would absolutely agree with him.

[sevensor]

Back in grad school, I had the pleasure of working with some very old FORTRAN. Written conservatively using a few bits of FORTRAN 77, but mainly in a FORTRAN 66 style. The control structures I found in there would make you go crosseyed. At one point, there was a jump that took you from outside a loop to the middle of the body of the loop. Today's no-longer-all-caps Fortran manages to elude EWD's criticism by not being that language any longer. You have to use a lot of obscure compiler flags even to make the old stuff compile.

[ThrowawayR2]

Having written code in the early microcomputer BASICs, I'm reasonably familiar with the context but I think it's a bit overblown. Sure, BASIC was limited in the syntactic sugar that was available to manage program complexity but, then again, the microcomputers of the era were so limited that complexity wasn't really possible without dropping to machine language anyway. And machine language definitely didn't have any of the syntactic sugar of ALGOL 60 or other high-level languagess.

[qsort]

As a massive fan of Dijkstra myself, true but up to a point.

About programming languages I don't think there's any question he was right. Sometimes we agree with him even without realizing it, for example, the original argument of GOTO considered harmful was that GOTO statements decreased "linearity" by having the control flow jump to random places. The recent trend in mainstream PLs to adopt functional-style control structures (JS array methods, Java streams, etc.) is predicated on the exact same rationale.

I'm also in broad agreement on his stance about natural language being just flat out wrong in the context of computing.

But the man made an exorbitant amount of claims, many of which are just provably wrong. The bits about BASIC and COBOL are particularly egregious examples of his at times cavalier attitude. After all, arrogance is measured in nano-Dijkstras.

[andi999]

The goto thing is one of my pet peeve, somehow it caught on, maybe it made people feel good so they can look down on others. There is basically 2 arguments against it: Knuths article arguing for goto (read it if you havent), and the observation that gotos and state machines (which are considered best practices) are basically equivalent (just convert the goto labels to your states).

[qsort]

I'm familiar with Knuth's argument. That argument was primarily based on the fact that it's hard to replicate the exact control flow of a goto statement with structured programming. While the argument certainly has merit (a relatively more recent example is Duff's device), 2020 compilers are more often than not able to find the most optimal structure anyway, making it largely redundant. It's like saying programs should be allowed to rewrite their machine code just because in a Von Neumann architecture you are technically allowed to, there is a point but it's not in contradiction with goto statements being mostly the inferior way to solve the problem. From a 2020 perspective I'd argue that if you really need that kind of performance you are probably already inlining assembly, so it's kind of a moot point.

> gotos and state machines (which are considered best practices) are basically equivalent

WTF? State machines can be implemented in a lot of ways: mutually recursive calls, pattern matching, function pointers... In what sense are they "equivalent" to gotos? Also what does it mean that state machines "are considered best practices"?

[brundolf]

Yeah. Much of this list simply comes off as arrogant and narrow-minded. Whether or not it was tongue-in-cheek, I don't know. This one in particular:

> It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration.

is at best a hyperbolic joke. I dearly hope he wasn't being serious.

[ThrowawayR2]

Dijkstra provides glimpses of his reasoning scattered across his missives. For example, for FORTRAN in https://www.cs.utexas.edu/~EWD/transcriptions/EWD03xx/EWD340...

"The second major development on the software scene that I would like to mention is the birth of FORTRAN. At that time this was a project of great temerity and the people responsible for it deserve our great admiration. It would be absolutely unfair to blame them for shortcomings that only became apparent after a decade or so of extensive usage: groups with a successful look-ahead of ten years are quite rare! In retrospect we must rate FORTRAN as a successful coding technique, but with very few effective aids to conception, aids which are now so urgently needed that time has come to consider it out of date. The sooner we can forget that FORTRAN has ever existed, the better, for as a vehicle of thought it is no longer adequate: it wastes our brainpower, is too risky and therefore too expensive to use. FORTRAN’s tragic fate has been its wide acceptance, mentally chaining thousands and thousands of programmers to our past mistakes. I pray daily that more of my fellow-programmers may find the means of freeing themselves from the curse of compatibility."

[brundolf]

I don't think any language that could ever be invented could be described as leaving programming students "mentally mutilated beyond hope of regeneration", no matter how bad it is. So either he was being hyperbolic (and the sarcasm was lost on me), or he was being shockingly dogmatic.

It's the kind of ranting you do with your colleagues in a pub after-hours, not something you publish in a professional context and frame as "unpleasant truths", as if they've been proven through scientific measurement.

[ThrowawayR2]

Tenured professors, particularly of EWD's stature, get a lot of license to say what they want. I can certainly a few of my instructors who were rather colorful in a variety of ways.

[brundolf]

I've no doubt they have license to do so without damaging their careers. That doesn't make it a good take.

[_u9xp]

Because it makes you uncomfortable? Or because you have reason to believe otherwise?

[IceCreamJonsey]

If you're used to exclusively programming with line numbers and you're a kid, sure, it might take a little bit of time and instruction to comprehend that line numbers aren't necessary. But from what he wrote it just sounds like this guy is whining about (when faced with students like this) having to actually do his job.

[Jtsummers]

Fortran and BASIC at the time were, in many ways, the antithesis to his ideas of what a programming language should be.

They did not permit recursion (direct or indirect). Almost by design they encouraged spaghetti code (the thing Structured Programming was meant to work against). They encouraged (or required) global state. They discouraged modularity. They were effective languages (in the sense that people got stuff done in them), but they were poor languages when compared to the capabilities of their contemporaries.

[GoblinSlayer]

I didn't have an impression that line numbers were important. Most of the time they did nothing and were unwieldy to maintain, they were more nuisance than anything else.

[User23]

I disagree and I believe most developers would agree that it would have been a far better use of time to learn 6502 assembly than Apple BASIC, at least if one's goal was to actually learn how to program computers.

To this day if I saw 6502 assembly on a resume I'd be intrigued and if I saw BASIC I'd view it as a yellow flag.

[brundolf]

Then you say "There are better options than BASIC for teaching new programmers." That's not what was written.

I've read countless anecdotes from perfectly capable programmers who not only learned, but first discovered their interest in the field, via BASIC. No language "mentally mutilates programmers beyond hope of regeneration". And BASIC probably isn't even the worst one for learning purposes.

[User23]

He calls out BASIC specifically because it was ubiquitous and often the only option on the machines novices would have available at the time. It logically follows that most programmers of that era, capable or otherwise, started on BASIC. Since he’s not here to tell us, I can only assume Dijkstra met the occasional exceptional individual who began learning to program in a more mathematically rigorous language during that time and was left with a vastly more favorable impression.

Remember, Dijkstra was a professor and he was an expert on teaching programming. He would have far more experience with the effect he claims than I do. I hazard to guess that is true with respect to you too.

And yes he’s obviously engaging in rhetorical hyperbole in the text you quote.

[ThrowawayR2]

> "He calls out BASIC specifically because it was ubiquitous and often the only option on the machines novices would have available at the time."

EWD's quote is from 1975 which is just barely the start of the microcomputer era (the Altair 8800 came out in '75 and the Apple II in '77), so he's not referring to those. Most people writing programs would have had access to mainframes and therefore had access to multiple language interpreters and compilers I would think.

[User23]

https://en.wikipedia.org/wiki/BASIC#Explosive_growth:_the_ho...

[GoblinSlayer]

People had to create specialized languages for learning purpose to compete with builtin graphics feature of basic.