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Comment by sillysaurus3 | Hacker News Reader

Because there are what, six types of bridges? (EDIT: 36 according to wikipedia.)

There are six thousand types of programs (as a wild guess), and they all interact with each other in an exponential explosion of complexity.

For a formal method to work, it has to be generally applicable across a wide range of situations. There are methods like that in software engineering, and you see them in situations where the program is potentially life-threatening. But most programs would be hindered by this rigor.

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I'll put it this way. In mathematics, the atomic unit of progress is the proof. Proofs are constructed from axioms and other, smaller proofs. The Curry-Howard correspondence is the direct correspondence between computer programs and mathematical proofs.

When programming in a well-typed language, everything we do is a degenerate proof of something. I think it's entirely reasonable to try and make it easier to make less degenerate proofs, and encourage the re-centering of proofs as the atomic unit in programming, because they are for programming (as in math) a well-defined, solid formal system that solid systems can be built on in a way that nothing else can be in software, at least thus far.

In a world where software flows more freely than water, the correctness and reliability of software systems must be taken with utmost seriousness. This applies to basically any tool that contacts end users, and a lot of ones that don't as well.

What do you propose as the theoretical basis for the engineering science of software development?

I think it's self-evident that there is no theoretical basis for software development in the way that would satisfy your criteria. Software dev is generally a scattershot haphazard endeavor that involves trying dozens of angles until one of them works. That's an unsatisfying answer, but if we try to hide from the implications just because we don't like it, we'll end up creating companies that fail to startups without these constraints.

It's also self-evident that in most situations, correctness and reliability aren't a concern. The counterexamples account for maybe 1% of the field. 99% of the time, if your program breaks, you can pay someone to go fix it and no serious harm was done. Even Github outages, which affect almost all of us, hardly matter.

>I think it's self-evident that there is no theoretical basis for software development in the way that would satisfy your criteria.

I don't think this is self-evident whatsoever. One of the problems in software engineering is that we never know when a solution is "right," we only know when it's vaguely not-wrong, and even then almost everything we create is still subtly wrong in a way we forgot to think about. Math is solid because there is certainty in the correctness of certain proofs, and these can be used as building blocks for further results. Philosophically speaking this is the closest we're going to get to "real" engineering practice in software, and we're pretty dang far from it if you know what that looks like.

>Software dev is generally a scattershot haphazard endeavor that involves trying dozens of angles until one of them works.

But this is a symptom of any pre-scientific field in engineering, it's not specifically endemic to software engineering. The main difference is that in software engineering we're applying math directly, and in other engineering fields we're applying science. In a certain sense, the natural sciences are purely empirical (modulo advanced physics of course, which overlaps with pure math and philosophy these days) while math and consequently computer science are purely rational. So, what are the solid elements in math? Proofs. Proofs are also how you ensure that the field actually moves forward and you're not stuck recreating solid results that already exist. Sound familiar? It happens constantly in software, but imperative and poorly-typed languages inhibit composability and reuse because they lend themselves easily to extremely specific solutions to general problems.

>It's also self-evident that in most situations, correctness and reliability aren't a concern. The counterexamples account for maybe 1% of the field. 99% of the time, if your program breaks, you can pay someone to go fix it and no serious harm was done. Even Github outages, which affect almost all of us, hardly matter.

This is preposterous. Just because lives are not in danger does not mean that it's not worth doing right by the solution, and frankly I think a lot more lives are waiting to be put in danger by crappy software with bad security than you realize. It's already become almost dogma that all software engineers need to have a deep understanding of security, and I don't understand why correctness can't fall under that rubric as well. If we're going to be having Geohot or even Google or whoever building self-driving cars for possibly billions of people, enormous critical infrastructure projects coming under computer control, etc, the whole industry from education on up is going to have to have a serious attitude adjustment to keep up with the demands of safety, security, and reliability.

It might not matter 99% of the time, (I think it's a lot more than that of course) but we need to make sure that we can as a discipline deliver that 1% when it is absolutely critical, and as of right now it doesn't seem like we can.

FWIW, we agree on this point. But it seems worth treating this 1% case as a separate discipline rather than trying to lump it together with software dev. No one would claim that NASA's software engineering is the same type of work as, say, writing a new HN feature.

It's already become almost dogma that all software engineers need to have a deep understanding of security

The most secure programs are those that undergo frequent penetration tests and have bug bounty programs. Speaking as a pentester, I think there's not much chance of regular software devs being any good at security. There's just too much to know.

I want to agree with your other points, because in principle it's the correct thing. Unfortunately experience has taught us that the correct thing usually loses in the real world. Being first to market mattered way more for Ethereum than the fact that the DAO had a bug in their smart contract, for example. But there are hundreds or even thousands of examples of this type.

If we pretend that a teenager hacking in their bedroom is doing something fundamentally different than what most developers do each day at their jobs, then we lose out on the ability of that teenager to innovate. We become an exclusionary clique rather than an inclusive group. Luckily market forces still prevent us from becoming that insular, but in the era of walled gardens it's easy to imagine we're not too far off from that fate.

The main issue is that if we try to restrict the free market e.g. with legislation, then the important work will simply move overseas to areas without those restrictions. And unless you're proposing legal restrictions on the software dev trade, it's unclear how to enforce any of the proposals upthread.

>No one would claim that NASA's software engineering is the same type of work as, say, writing a new HN feature.

Well no, but the same underlying principles are still operating. The only difference is how much you care about heeding them. You don't need an aerospace engineering degree to make a paper airplane or a short bridge or a raft or whatever, but that doesn't mean that your knowledge of how to do so reliably and correctly wouldn't be improved by such a degree, or that if you're going to sell a product that you hope people will pay you for and subsequently depend on that you shouldn't bother trying to make it functional (in the "it works" sense) to the best of your abilities.

>If we pretend that a teenager hacking in their bedroom is doing something fundamentally different than what most developers do each day at their jobs, then we lose out on the ability of that teenager to innovate.

Ok, that teenager can hack, sure, just the same as they can build a two-stroke engine or an electronic alarm for their door or play around with nuclear fusion or whatever. But if they're going to sell those things and make claims about their safety and reliability, the validity of those claims should be enforced by an industry guild accreditation program or legal regulations or whatever. There's more than one way to skin this cat, but it really needs skinning.

>The main issue is that if we try to restrict the free market e.g. with legislation, then the important work will simply move overseas to areas without those restrictions.

The goalposts are being moved here, though, near as I can tell. I told you what I wanted done and why I thought it would work, and now you're telling me I have to figure out how to do it specifically in such a way that it can't be circumvented. I haven't thought up a specific solution to this question you pose, and as such I would point you in the direction of how liability works in other disciplines for similar cases and so on. I do actually think a lot of the same systems could work for enforcement, the biggest difficulty is actually figuring out what the principles should be. If the biggest problem with enforcement is that teenage hackers can't innovate anymore, I'm not really all that concerned. Romanticizing that image does nothing to change the hard realities of the industry.

> Well no, but the same underlying principles are still operating. The only difference is how much you care about heeding them. You don't need an aerospace engineering degree to make a paper airplane or a short bridge or a raft or whatever, but that doesn't mean that your knowledge of how to do so reliably and correctly wouldn't be improved by such a degree, or that if you're going to sell a product that you hope people will pay you for and subsequently depend on that you shouldn't bother trying to make it functional (in the "it works" sense) to the best of your abilities.

Not really. The time scales are completely different: that HN feature that is schedule a week of dev time is incomparable to that probe feature that is scheduled years of dev time even if the amount of code involved is the same. You could argue that both are "just programming", but the activities and process involved in both are going to be completely different.

>The time scales are completely different: that HN feature that is schedule a week of dev time is incomparable to that probe feature that is scheduled years of dev time even if the amount of code involved is the same.

You missed the point though. Whether it takes you five minutes to code the feature or fifty years, you're still doing math. The so-called "engineering" principles might change, with regards to division of labor and so on, but the underlying science/math you're dealing with doesn't significantly.

And this is the difference between math and engineering: in engineering you just have to be close enough to perfect that it doesn't break in the real world. It can never be absolutely perfect, because that would be either physically impossible or too expensive. This is true for mechanical, civil, chemical, and yes, software engineering.

In engineering the time it takes to implement the design/proof/code/output is one of the constraints. In math this constraint is ignored.

How are you "doing math"? Math might be involved in the feature, but many features just require lots of pattern matching and decision making. Maybe for some vaguely definite non-specific definition of meth that also encompasses most of human thinking this is true, but I fail to see how that is useful.

> I think there's not much chance of regular software devs being any good at security. There's just too much to know.

I have over 30 years of experience and I couldn't agree more. The security field - heck, the website security field - is way too complex for me to navigate it properly. Sure, I know about SQL injection, but "authentication is not authorization" is something I tend to forget, and I am pretty sure I have no clue about at least half of OWASP top ten.

"If we pretend that a teenager hacking in their bedroom is doing something fundamentally different than what most developers do each day at their jobs, then we lose out on the ability of that teenager to innovate. "

That all contributors don't have the capability to formalize their output has never been a viable argument against formalization.

Before music education was formalized music was a mysterious craft you could only learn by learning with a master for a decade if you weren't incredibly talented.

Once the orphanages of Naples formalized music teaching in the 17th century it became something much easier to learn and teach.

Sound familiar?

Yet, music teaching did not eliminate the capability of non-formal craftmen to innovate. They just have collaborators to help formalize their thought process.(John Lennon did not know music theory and still made awesome stuff. But without formal theory his output could not live on in sheet music, and it would be a lot harder to reproduce it).

Even Einstein needed help with his math. But without math, theory of relativity would not have been much of anything.

It's all fine to imagine one is traveling in a traincar, but once one needs to compute, say, the orbit of mercury all need formal methods.

Creativity and formalism go hand in hand. You need both for a superpowered discipline.

Looking at the discussion around your and Turing_Machine's points, I think one could generalize the problem like this: in a large and complicated search space, finding a solution is much faster and cheaper than trying to comprehend and formally describe the search space (to later derive the solutions). The up-front costs of doing the latter are so high (I don't think we even have a good bounds on them) that nobody who needs a solution bothers with it. Iterative search is the only way individuals and teams can feasibly find the solution they're looking for.

This way, I think formalizing software development is a worthwhile goal - just like formalizing cooking is - but it's also obviously so uneconomical that we can't expect the industry to bother with it. Formal methods are pretty much basic research - not useful for us in any meaningful timeframe, but hopefully our grandchildren will get some mind-blowingly amazing tools out of it.

I havent thought of this before but i was a mathematician that does software engineering, and Im starting to see some stark similarities between a mathematical proof and a "test" as in a unit test. I imagine if you went down this road you would end up with something very similar if not identical to TDD. What i was hoping this thread would discuss is how to turn software design patterns like the adaptor or factory patterns into a science in the same way that differential topology turns differential equations from a haphazard collection of methods into a rigorous science. I dont know why more people havent focused on formulating this more practical side of software engineering. Why is it that SOLID works so well, etc

Yes, this is of extreme interest to me as well. The why behind SOLID. I think you could formulate more rigorous support based upon information and graph theory, maybe neuroscience, and other areas I'm less familiar with.

For example, the Single Responsibility Principle (SRP) is primarily concerned with making software more manageable on both an individual and team basis. How? By minimizing:

1. Communication overhead between teams/modules

2. Information overload in an individual

You could look at #1 from a graph-theoretic and information basis. I'm sure there are many interesting things to prove there. Like Amdahl's and the opposite of Metcalfe's Law [1][2] applied to team/communication/module dependencies. Just as a basic example, if one class has 10 responsibilities shared by 10 engineers with no boundaries specified, then the probability of conflict and unintended consequences rises. Thus the rate of development slows.

As for #2, applying more rigor and proof to the question of how these principles help a human understand quicker.

I don't have the necessary background right now to explore this in more detail, but like you, I'm very interested in any possible formulations.

[1]: https://en.wikipedia.org/wiki/Amdahl%27s_law

[2]: https://en.wikipedia.org/wiki/Metcalfe%27s_law

The problem is that even things like "how many people touch this class" and "how many external teams do we work with" aren't simple at all. Some external teams are much easier to work with than others. Sometimes you want your whole team to intimately understand an area of your code. Making software is an intensely human process, which is why managing software teams is almost entirely about considering the people on your team, and what makes each of them different.

Dijkstra spent a lot of his research effort on ways to prove that programs are correct.

"Today a usual technique is to make a program and then to test it. But: program testing can be a very effective way to show the presence of bugs, but it is hopelessly inadequate for showing their absence. The only effective way to raise the confidence level of a program significantly is to give a convincing proof of its correctness."

https://www.cs.utexas.edu/users/EWD/ewd03xx/EWD340.PDF

"I don't need to waste my time with a computer just because I am a computer scientist." - Dijkstra

This basically describes the dichotomy between CS and software engineering.

There is great wisdom in that observation, but I also enjoyed Knuth's take on the matter:

"Beware of bugs in the above code; I have only proved it correct, not tried it."

http://www-cs-faculty.stanford.edu/~knuth/faq.html

Tests are negative proofs; you can show that a specific invocation doesn't fail. But unless they are exhaustive over the input space, they are never positive. You can't say something works universally.

I am not a full subscriber to SOLID. I think it promotes a certain kind of degenerate over-abstraction that leads to bugs of a different nature, premature decisions on what needs future substitution, and decreases agility in the medium term.

> scattershot haphazard endeavor that involves trying dozens of angles until one of them works

Sounds a lot like engineering/design/art. There's a large amount of overlap between the three.

I had the pleasure of speaking to the principal electrical engineer whose firm was responsible for designing the entire electrical system for One World Trade Center in Manhattan and the Citi field as well.

He described his work a lot like a software developer would describe their own. And then, in his words, when his company was done they "passed the plans over to the electricians to build it".

It just so happens, in our profession, we've automated the part that electricians are responsible for in his project. Our electricians are called compilers. They dutifully carry out the plan and from time to time they surface warnings/errors back to the engineer for input/correction.

People conflate the meaning of software development because one person shares so many different responsibilities, that are usually handled by separate people in other professions: architecture, design, analysis, implementation, maintenance, etc.

What a civil/electrical/mechanical engineer does isn't so different from what a software engineer does. It's a "scattershot haphazard endeavor that involves trying dozens of angles [based upon guiding principles] until one of them works" usually run through loads of simulation and analysis. Now, the difference is, when these engineers want to bring their idea into the world it takes physical labor, unlike software development where the feedback loop is near instantaneous. We bring our programs into the world with compilers and can run them immediately.

I mean, there are plenty of examples where civil/electrical/mechanical engineers failed in their design and thus created a bug in their project. See [1] or any contemporary CPU from AMD/Intel or automobile recalls or spacecraft failures, etc.

There are certain principles of software engineering that lead to more effective software. That's a fact. And the companies that understand this fact will not fail to startups, in fact they exhibit a severe technological advantage.

Google and Facebook are two companies that understand software engineering. Talk to the YouTube/Instagram teams and see whether they felt better off -- technologically -- before or after acquisition.

[1]: https://en.wikipedia.org/wiki/Citigroup_Center#Engineering_c...

Agreed. Reading [1] was a fantastic eye-opener for me. The code is the design, and design is always "trying until it works".

[1] http://www.developerdotstar.com/mag/articles/reeves_design.h...

That was a great read, thanks for that. Indeed that article really codifies a lot of the thoughts that have been floating around in my head.

> Software dev is generally a scattershot haphazard endeavor that involves trying dozens of angles until one of them works.

So software engineering isn't engineering, either? I would imagine any civil engineer who actually knows what it takes to build a bridge would tend to agree, at least on the basis of the points you have put forward so far.

if you look at civil engineering at it's childhood stages that is, back when pre-historic man tried to build huts and lean-tos, you'd find that they too, didn't use any solid engineering practises, but simply tried different things and found out what worked. Being constrained physically makes it easier to determine what works, but the essense isn't any different to what software engineering is today.

I bet if we fast forward 1000 years, you'd find that software engineering will have become as rigorous as what we have today in civil engineering.

This. Someday software developers will look back on us the way doctors look back on barbers' bloodletting.

Now that we brought out the doctor analogy, I have news for you....doctors deal with an unknown system, gain personal and institutional experience through trial and error, are basically detectives, are rarely working with full information, and have, despite their heroic efforts, a significant task failure rate (the patient dies).

How is that not like software engineering?

i dont think doctors fail as often as software projects. and they only fail on the fringes of medicine - like treating cancer, or rare diseases. You don't often see doctors failing to treat the cold or a broken angle badly that they kill their patients!

But in the software world, it seems the equivalent of the cold is a CRUD app, but still fails so often that it's newsworthily talked about when such a software project succeed!

No, that's not equivalent. A doctor treats a cold the same in every case. Software engineers are building different systems for each case, or else they would just use existing software.

Part of that is because software development is usually concerned with optimizing things for their sale value, not for being useful. In my example, a lot of problems could easily be solved with the same CRUD stack, if not for the needs concerning the design (i.e. it can't look similar to that competitor's thing) and other goals unrelated to actual use of the product.

A doctor doesn't really treat a cold though. They can treat an infection with anti biotics, they can treat something more specific than a cold with something. But if you come in with just a typical cold and say "treat me," they'll give you a placebo and prescribe lots of rest and water.

> I bet if we fast forward 1000 years, you'd find that software engineering will have become as rigorous as what we have today in civil engineering.

This isn't evident at all. In software, every situation is novel, so there is no room for repeatable processes.

You can build a "bridge library" once and tweak it for each situation, but you never need to develop a rigorous process to build that library again.

> every situation is novel

this is the point i m contesting - that most situations aren't as novel as the stakeholders think it is. The failure happens because the assumption that it's novel is there!

In general there may not be that much novelty per project, but that isn't the novelty that one needs to worry about in software projects. The relevant novelty is the novelty to the project team. Also lot of the novelty comes not from the technical side, but domain and organization that will be using the software.

This is a big argument in favor of experienced devs, who have deep technical and domain expertise.

Not really familiar with RTOS/embedded/security/military/medical software then, are we.

If those examples are 1% of software, they take disproportionately more funding than 1%.

And I'm sure customers of software, from personal computers, to business apps, to corporate websites would appreciate more consistent results as well. Reckless software engineering has damaged the reputation of the field as a whole.

>I think it's self-evident that there is no theoretical basis for software development in the way that would satisfy your criteria.

Yes. Writing software is not math. Does it use math concepts? Of course, but so does just about everything else. While we're at it, writing software is also not engineering, even though there are engineering concepts that can be applied.

Writing software is its own thing. Pretending that it's something else (like math or engineering) invariably leads to category errors.

Think about food recipes. They certainly use measurements and timing, and engineering principles can certainly be applied (especially when executing them on an industrial scale) but they are not math (or engineering) either. Examining the measurements, timing, and the production chain doesn't tell you anything about whether the recipe is delicious or inedible.

Arguing that a piece of software should be "proven correct" makes about as much sense as arguing that a recipe should be "proven correct". You might as well judge the recipe by the standards of poetry ("Does it have evocative imagery? Does it rhyme or alliterate well?").

People have been chasing the unicorn of software correctness proofs for 60 years, with a notable lack of generalizable success (there are plenty of toy examples, of course). What usually happens is that the "programming is math" people come up with some bizarre academic language that no real-world programmer would use unless forced to do so at gunpoint (followed by the new language sinking without a trace). Alternatively, the "programming is engineering" people come up with some baroque formal process that requires you to write a 500 page document and get six committees to sign off on it before you can write "Hello, world". I'm old enough that I've seen these things happen multiple times.

>It's also self-evident that in most situations, correctness and reliability aren't a concern.

I wouldn't say they aren't a concern at all, but if you're wasting six months screwing around with formal proofs, UML diagrams, or things of that nature, while in the meantime your competitor is iterating three or four times, that is definitely a concern. Operate that way and your milkshake is going to be drunk, yo.

>Writing software is not math.

You're wrong, and I've explained this upthread.

>Think about food recipes.

Do you have experience with non-imperative programming paradigms? I'm sorry to say that the comparison to recipes in this context seems fairly naive.

>People have been chasing the unicorn of software correctness proofs for 60 years, with a notable lack of generalizable success (there are plenty of toy examples, of course).

Static type systems are arguably a product of this, especially advanced ones like Haskell's.

>What usually happens is that the "programming is math" people come up with some bizarre academic language that no real-world programmer would use unless forced to do so at gunpoint (followed by the new language sinking without a trace).

Now you're just being anti-intellectual. The whole point is that the real-world programmers are stumbling into all this crap constantly without realizing it. It's completely fucking unavoidable and very much tied up with the fact that programming is math. The only question is what you choose to do about that: learn the math, or stay ignorant.

I don't mean to be condescending but I find comparing UML diagrams and proof assistants a little offensive (among other things), and it suggests you don't know what you're talking about. Modern proof assistants and other formal techniques like dependent typing happen while you're programming (Idris/Agda) or generate programs themselves (Coq), they aren't some sort of Waterfall-ish thing where you have to deal with all the ceremony before you start to get shit done. On the contrary, you get shit done, and it works better when you're done with it too.

Your post contains a lot of unnecessary aggression. Rather than suggesting someone "doesn't know what they're talking about", just provide evidence to the contrary.

That aside, there seems to be something missing in your analysis, or there would be a lot of successful startups stealing the market using proof assistants and formal techniques. It's not anti intellectual to point out that programmers don't want to use academic languages that have poor usability, steep learning curves, and garbage for standard libraries.

Consider when a regular house is being built. There are many problems that could be avoided if an engineering firm spent an entire year analyzing the designs and their interactions with the target site. However, that's not done because it takes significantly longer and costs obscene amounts of money.

It's easier for the construction crew to fix problems as they encounter them and for the owner to do repairs on the house 40 years later. Yeah, the house isn't as reliable, but it cost 100,000 instead of 1,000,000.

If you want developers and managers on your side, you need to show them benefits over the quick development of python/php/Javascript other than bugs in edge cases being less frequent. Don't just bemoan how unenlightened everyone is.

While it is true a full formal proof of a C++ program, for example can take significantly longer and cost obscene amounts of money, that is not true when starting with this approach from the ground up.

There is also a certain level of compromise. By relaxing the requirements a tad, you can still gain many of the benefits while maintaining the light and nimble feel.

So why don't startups use this? Well because there are entrenched technologies that make it very difficult that have nothing to do with the merits of the approach itself.

It is up to us, as developers to take the charge and push for these techniques through open source development, advocacy, and training.

But to claim these techniques are a failure simply because startups aren't using them is pretty ridiculous.

Higher assurance from the start requires something functionally similar to Ada's Spark.

I've never seen that used in the wild (though I'm in the wrong domain (web) these days).

Well, all the naysayers could also do some research instead of being as dismissive as they are. Here's an example of actual use of formal methods: http://lamport.azurewebsites.net/tla/amazon.html Why aren't they used more widely? Because when people hear"math", they immediately think of it as academic. It would also be overkill for most projects.

TLA is one of the systems that are actually very practical. You can go up or down as many abstraction layers as you need . There's a great introduction written by @pron on his blog [1].

However, it's worth pointing out that you don't magically get the final program out of the TLA proof. The proof only works for the abstraction level that you chose to write it at.

[1] https://pron.github.io/

>>Writing software is not math.

> You're wrong, and I've explained this upthread.

I suspect there is a difference in semantics, here. Software is inherently mathematical, yes. But the practice of writing software is not the practice of doing math.

The output of doing math is proofs. The output of writing software is...something that does something when run on a computer, hopefully interesting, meaningful, useful, or entertaining. In the vast majority of cases, we have not and will not need formal proofs of correctness for software to achieve these things.

If I want a blur effect on some portion of a UI, and choose to implement that with a Gaussian blur, what value is there in formally proving that a specifically Gaussian blur has been applied? All of this is inherently mathematical, but that doesn't imply a need for mathematical proof.

I agree. It's kind of a focus thing. When I'm writing code, I do it because I want stuff to happen - in real life, in our physical reality. Any concept of code-as-a-proof is not even on my radar, unless I'd be writing life-critical software for NASA or a hospital, or something.

Here I also thing that 'Turing_Machine is both wrong in details and correct in the general point with their recipe example:

> Examining the measurements, timing, and the production chain doesn't tell you anything about whether the recipe is delicious or inedible.

You could, in principle, apply the knowledge of medicine, chemistry and biology, coupled with process engineering and wide-scale people studies, to construct a theory of tasty foods, which could lead to the situation in which you could evaluate any recipe on a theoretical basis. But getting to that state would require tons of up-front work to be done (some of which is being done for unrelated reasons, so maybe in the future a "food theory" will assemble itself) - and in the meantime, getting a piece of tasty food is done much faster and cheaper by finding the solution instead of deriving it. This search is done through iteration.

Similarly, in software, 99% of the time we find a solution, not derive it from first principles - because the former is much cheaper when we care about the solution, and not solving the entire general class of a problem at the same time.

The same is true for math. It is the same thing, because of the Curry-Howard isomorphism.

The reason for all the confusion is that programmers are already doing math. They just don't realize it and reinvent the wheels invented by the math community in the past century. It's a matter of semiotics.

Nah, I still think it's about different goals.

But assuming you're right, I'd like to know - what mathematical wheels am I reinventing in my dayjob of building UIs that let people click up some stuff that later gets put in business-specific XMLs?

You're defining relationships between types through functions.

Math, at least applied math, is not the goal, but the method. Programming neither is the goal, it is the method. Understanding that both are language to express the path is of the essence.

The XML as a vessel of human-knowledge is limited. Good intentions have brought it OWL/RDF, XML Schema, XSLT; examples where others before us have tried to extend the XML into the domain of semantics and algorithms. Nevertheless, it was found that, without an expressive type system, large and complex business domains cannot be modeled. Apparently, in order to model abstract business domains, we need a language that composes both high- and low-level with near invisible seams.

So, that click-your-XML-application might benefit from a reflective logic, enabling the user to explore the possible state-spaces. If your app uses relational algebra from DBMSs, it might be able to combine the relational algebra with the algebra defined by your schema's. The UI state-space and the XML schema might be an isomorphism, which helps prove completeness of your UI-builder implementation.

Above all, the mathematical way of thinking helps reasoning, communication and correctness. It might not be the only way or perhaps the way is dated. Nevertheless, ignoring math as a programmer, feels like ignoring music theory as a musician or linear algebra as a structural engineer.

We haven't been arguing that programming can't benefit from math.

> ignoring math as a programmer, feels like ignoring music theory as a musician or linear algebra as a structural engineer.

We're not ignoring math.

Curry-Howard isomorphism does not mean the same practices that are performed in mathematics research must be applied to writing software.

Some aspects of language design are reinventing wheels invented by the math community. This is far from constituting the set of "writing software" or "software engineering".

What is there to prove in most cases though? I spend half my time redefining requirements.

I like Idris, and there's room for these languages. I think you give them too much credit though, programs written in them still have bugs. Your spec can be wrong. But above all else, they can't help you with scale, performance, recovering from hardware faults, and delivering what users wants.

The languages are still new, they'll gain traction, and for certain use cases they'll make sense, for others they won't.

The reason to use formal systems is to be able to reason about larger, more complex systems. Our brain is rather limited and to empower ourselves, we've found the divide and conquer approach. For that to work, we need assurances that our composition is correct due to the subcomponents being correct (and the composition operator). This is something we do all the time. You assume your compiler is correct, or your common libraries. However, if we want to grow larger systems, our foundations become more critical and we need stronger assurances.

Surely you can see the part about recipes was an analogy to make a point and not directly equating two?

I think you're dismissing the post without engaging its arguments, so it hardly seems fair to start calling people naive, anti-intellectual, and ignorant. (btw, we all get that these are different ways of calling someone stupid, which is never productive and isn't justified in this case.)

To attempt to engage your argument, as far as I understand it... i think type systems and programming paragidms, however formal, can at best solve problems only in a corner of the problem set of software development. The limitation is because these do not take into account various kinds of constraints on software systems which nevertheless exist and are often the dominant constraints, depending on the project... Requirements, maintainability, usability, estimation, etc -- most of the stuff above the red line from the article.

I don't consider myself anti-intellectual, and I wrote a blog post on my claim that computer science is not math: http://www.scott-a-s.com/cs-is-not-math/ We discussed it a few years ago: https://news.ycombinator.com/item?id=3928276

> You're wrong, and I've explained this upthread.

No. I'm not.

Are formal math and engineering useful in cooking food? Yes, they can be (particularly if executing on an industrial scale). Are they necessary? Not really. Plenty of great cooks just throw in ingredients in the amounts that seem right to them, perhaps tasting the result once in a while. Are they sufficient? Nope. If the best mathematician and best engineer in the world collaborated, the result might be edible or it might be an inedible mess.

If neither formal math and engineering are necessary nor sufficient to produce good cooking, we can safely conclude that cooking is not math or engineering.

> Static type systems are arguably a product of this, especially advanced ones like Haskell's.

Haskell is used by, to a first approximation, no one. Which was my point.

> Now you're just being anti-intellectual.

No, I'm not.

> The only question is what you choose to do about that: learn the math, or stay ignorant.

I was one math class away from getting a dual BS in math and CS in undergrad. Rather than stick around for another semester, I took the BSCS and went to grad school.

You can safely assume that I "learned the math", and that I am not "anti-intellectual".

The point here is that while, on the most fundamental level, the universe may indeed be made of math, that doesn't mean that treating everything with the math toolbox is the best way to proceed. Expecting that math methods will produce great software is a fundamentally goofy idea -- just as it would be to expect math to produce great poetry, painting, architecture, or anything else (and the same for engineering).

>If neither formal math and engineering are necessary nor sufficient to produce good cooking, we can safely conclude that cooking is not math or engineering.

Bingo. Good thing we're talking about programming, and not cooking.

I asked if you understood what you were saying because you can't really cook declaratively, recipes are inherently imperative. The comparison to programming thus only fits for imperative languages.

>Haskell is used by, to a first approximation, no one. Which was my point.

If that's your point, then I agree. Not sure how that's in disagreement with my points though.

>No, I'm not.

So what then were you intending to convey by vague references to incomprehensible academia? Surely you weren't meaning to imply they're just wrong, were you?

>The point here is that while, on the most fundamental level, the universe may indeed be made of math, that doesn't mean that treating everything with the math toolbox is the best way to proceed.

Yes, but such a general claim is not what I'm arguing for.

>Expecting that math methods will produce great software is a fundamentally goofy idea -- just as it would be to expect math to produce great poetry, painting, architecture, or anything else (and the same for engineering).

Well, it of course depends on what you mean by "great" software. But I still think you're missing the point here. Computer science is a lot closer to math than poetry, painting, and architecture are. There is a direct, elegant, simple, formal correspondence between programs and proofs. The same cannot be said for those other disciplines.

My only claim is that proofs are slightly more solid intellectually and formally speaking than programs, so converting more programs into proofs will make easier to reason about, and since programs can be easily converted into proofs (relative to poems or architecture or paintings or whatever) that this is probably a good idea. I still don't understand what your objection to that claim is.

>>Haskell is used by, to a first approximation, no one. Which was my point.

> If that's your point, then I agree.

You are agreeing to something that is false. See my reply to the grandparent.

> The comparison to programming thus only fits for imperative languages.

I am not comparing recipes directly to programming. I used recipes as an example of something that has mathy and engineery facets, but that is not engineering or math.

> So what then were you intending to convey by vague references to incomprehensible academia?

I wasn't making "vague references" to anything, nor did I say that academic languages were "incomprehensible". I did say they were bizarre, which is a different thing entirely.

I'm not sure why you find it hard to believe that someone could understand academic languages of the sort you evidently prefer, and yet somehow still choose not to use them. Your attitude seems to be that anyone who doesn't use your preferred methods is "anti-intellectual", "ignorant", or any of the various other personal insults you've used.

Why not just go off and write some awesome software using your methods? If they work as well as you claim, you'll have some hard evidence to back up your assertions

>There is a direct, elegant, simple, formal correspondence between programs and proofs."

You are defining great software as "software that can be proved to behave in accordance with some formal spec", while people who actually use software (i.e., the people who pay the bills) define great software as software that performs the task they need to have done, can be written economically, and that is easy to use.

By your definition, a great recipe would be one that came out exactly the same every time, even if it tasted like shite, or took three weeks to make, or...

> Haskell is used by, to a first approximation, no one. Which was my point.

Unless you have a very loose definition of"no one" that simply is not true.

Just off the top of my head:

Haxl at Facebook Bond at Microsoft Supply chain management at Target

Also see:

https://wiki.haskell.org/Haskell_in_industry

>Unless you have a very loose definition of"no one" that simply is not true.

What part of "to a first approximation" was unclear?

https://www.tiobe.com/tiobe-index/

Haskell is in 47th place, which is consistent with where it ranks in every other popularity list I've ever seen.

I'm standing behind "to a first approximation, nobody".

Note that I'm not saying that Haskell is a bad language, or that Haskell programmers are bad people or anything like it.

I'm saying that the vast majority of programmers do not use Haskell. An anecdote about a particular group that uses Haskell (or even several groups) does nothing to refute that fact.

The Curry-Howard correspondence says that a program is the same as a proof. A proof of what, though? Not that the program does what it's supposed to. No matter how far you go with formal methods, what the program is supposed to do is always informally specified. (There may be a formal specification. That specification wasn't handed down from on high at Mount Sinai, though. It's a formalization of the informal, badly-stated, half-unconscious informal specification that is the impetus for creating the program. Does the formal spec match the informal one? Can you prove it? No, you can't - certainly not formally.

It's like you read the article, and set about disproving it, without ever really understanding it.

well that pretty much nailed it.

> Software dev ... involves trying dozen angles until one of them works

It is a way to solve mathematical problems, See "Guess and Check" from this book https://en.m.wikipedia.org/wiki/How_to_Solve_It

> I think it's self-evident that there is no theoretical basis for software development in the way that would satisfy your criteria. Software dev is generally a scattershot haphazard endeavor that involves trying dozens of angles until one of them works.

But the actual practice of doing mathematics (i.e. coming up with novel proofs) works exactly like this as well. The differences are in how much confidence we have in the results, and how much we're able to reuse them.

> It's also self-evident that in most situations, correctness and reliability aren't a concern. The counterexamples account for maybe 1% of the field. 99% of the time, if your program breaks, you can pay someone to go fix it and no serious harm was done. Even Github outages, which affect almost all of us, hardly matter.

I agree that we collectively don't currently care as much about correctness as we pretend we do. I believe software correctness is becoming more important (e.g. the rise of ransomware) and is going to become much much more important, but that's due to what I accept is a non-mainstream view of the future.

> Software dev is generally a scattershot haphazard endeavor that involves trying dozens of angles until one of them works.

Maybe in an agile web startup. SW engineering in a big industry project is a very deliberate process. You start by a requirements engineer writing very precise requirements. Then a SW engineer turns this into a module design and a test specification. These are turned into source code (for which we use code generators to an ever higher degree) and test cases by yet other SW engineers. In the end everything gets reviewed and/or tested.

Trying things until they work is just not done. That would be way too dangerous for SW that controls cars, airplanes, nuclear power plants, rockets etc.

Safety critical software is a small subset of the software that gets written in "big industry" projects.

There are hugely more systems not written to that standard.

Yes, but those systems are engineered in the exact same processes. Just with less testing and fewer documents.

Software engineering isn't math research. While I'm not against making it easier to formally prove correctness, at the same time I'm not sure why you think it's so important. We've been doing pretty well without it. How do you justify your certainty that we need it?

"How do you justify your certainty that we need it?"

Not OP but all pre-scientific crafts from medicine to construction have benefited considerably of application of formal methods. I don't see why software engineering a should be different.

How many doctors in the field are practicing formal methods these days beyond say statistics?

Anyways, surely SE as a field benefits from formal methods like other fields, whether applied by specialists or in the field by practitioners we can debate, but hopefully we can all agree SE isn't defined as just applying formal methods, that there is a lot in development that will never go near a formal spec.

Doctors are required to have extensive knowledge of chemistry, physics, and biology before even beginning medical school. Those are all highly scientific fields with centuries of practice behind them, not to mention medicine itself which is nearly as old as people are.

Yes, but computer scientists are required to take engineering physics also, as well as creative writing sometime. We are talking about the practice of medicine, and if you know any doctors, they aren't exactly very interested in math (they have a lot of other stuff to do!).

I'm not required to take any physics in my degree actually.

UW CSE requires first year engineer-level physics. I don't think that's unusual.

"we can all agree SE isn't defined as just applying formal methods, that there is a lot in development that will never go near a formal spec."

I've yet to see a field without artificial restraints that has abandoned need for human intuition and creativity.

The difference is that software development interacts with life, and that's where most problems lie: specifications from people who don't actually know what they need; interaction with ill-defined data and systems; unforseen cases; and everything changes over time, beyond the scope of the project.

I suppose that life is irregular.

There are multiple problems here, and they all stems from a lot of misunderstandings. Disclaimer : i do have a maths background and formal methods do have their use. But not in the general case.

>they are for programming (as in math) a well-defined, solid formal system that solid systems can be built on

Except you forget one big thing. Maths do not deal with errors or real world complexity. Maths exists by themselves in a world where errors and failure at other level do not exists. And i will not even talk about Gödel incompleteness or Turing proof of the the halting problem as other fundamentals mistakes here.

> can be built on in a way that nothing else can be in software, at least thus far. What about System Engineering? Because guess what? Other complex systems exists in the Nuclear, Space, Chemical or Aviation industry. And they are not developed with formal proof... and they still do work... But they use Engineering, proper one. Not wishful thinking and all.

>In a world where software flows more freely than water, the correctness and reliability of software systems must be taken with utmost seriousness. There is a really really small but essential mistake here. Two to be honest. The first one is that any sufficiently big software can not be proven correct and reliable. That is what Complexity Theory tell us.

But most importantly, it does show a complete lack of knowledge of the meaning of the word reliability and the research in Complex System. Reliable and Correct systems are inherently dangerous. What you want is a system that is SAFE. A system that is Safe, is a system that accept to do the "wrong" thing if it is the safe things to do.

>What do you propose as the theoretical basis for the engineering science of software development? Complex System. SNAFU catching. Stop trying to ignore the stack we live in and begin to think about runtime instead of over complex architecture. Safe guards and operators. Debugging as a first class citizen. Bulkheading and recovery. In general, System Engineering and Human Factors.

You can begin with reading web.mit.edu/2.75/resources/random/How%20Complex%20Systems%20Fail.pdf then follow with Nancy Leveson free book https://mitpress.mit.edu/books/engineering-safer-world .

PS: oh by the way, to everyone saying that other Engineering discipline are based on rigid step-by-step methodology that enforce correctness. It is not. It is even more a mess with slower feedback loop. I worked in other engineering fields before IT and it is not really better. It seems to be really American to believe in the "scientific method". But that does not exist. The world outside is messy and complex.

Try accepting that. There are solutions, but by living in a dream, you are working around the bug instead of fixing it.

And I'd argue that for a whole bunch of applications and software systems these days correctness has no business value.

I've been doing a lot of low-ish level programming with video hardware on an embedded system. I mmap a buffer, which gives direct access to the hardware. I trust that the driver reports the correct size of the buffer, and that the hardware puts the bits in that buffer in the way its spec promises. How the fuck do you formally prove any of that? I can prove that my software, for example, moves bits from offset x to offset y in the buffer correctly, but how do I prove that it makes sense to move those bits in that way? Or that I have interpreted the driver's documentation correctly, or the v4l2 API correctly, or that the hardware or driver does what it says it does? Keep in mind that this is C++ of course, so there's no mathematically rigorous type system; I just have a uint8_t pointer to a place in memory.

I can potentially lay down a bunch of assumptions, and prove that, given those assumptions, my program acts correctly. However, most of the bugs arise from incorrect assumptions.

One concrete example: When feeding pixel data to the onboard hardware h264 encoder's driver, after having set a resolution of 1920x1080, the resulting h264-encoded frame will be displayed in a h264 decoder with a resolution of 1920x1080. This turned out to be wrong, because the hardware can only deal with blocks of size 16x16, so the width and height must be a multiple of 16, and the driver isn't smart enough to add the necessary metadata to make a decoder crop it, so there's 8 green (because YCbCr) pixels on the bottom of the video. The solution to this is to manually splice the h264 bitstream, to insert my own metadata which has the correct cropping. How the fuck do you formally prove any of that?

>Keep in mind that this is C++ of course, so there's no mathematically rigorous type system; I just have a uint8_t pointer to a place in memory.

Well you basically answered your own question - you would need a language with a more sophisticated type system. You would then need an API/DSL to interact with the graphics hardware.

Six types of bridges... Were you serious? There are definitely ways to apply formal engineering methods to software that greatly help its development.

Computer programming is not a special snowflake. It's a field that (in many areas) refuses to grow up.

Forcing it to grow up would harm it, though. The engineers would move to companies that don't force those kinds of constraints.

It's important to keep in mind what "growing up" translates to: slowing down. This has both economic and competitive implications. Sometimes it might be a win, but the vast majority of the time your ability to move quickly (and yes, occasionally break things) is an advantage.

Yes and no. It is a natural progression of the industry. Those who cannot do "formal engineering" probably don't belong in engineering roles. Engineering, in general, imho, can be distilled down to this: Clearly define the constraints in which your project will operate under and prove that they will hold under those constraints. If someone as an SE cannot do that, they really have no business being anywhere near any field of engineering.

Depends on the constraints you want to prove that the program will uphold. Some constraints may be impossible to prove, especially in non-real time contexts.

For example, a program must run on a platform that doesn't have everything formally defined or have guarantees. If a program relies on that platform and that influences the program in a way that makes the constraint reliant on the platform, then you are out of luck.

Another issue is choosing the constraints that the program will operate under. You would hope that the clients would give you the requirements including the constraints the software must operate under. But this isn't often the case. Having an incremental approach which includes clarifying requirements by mapping what the clients need to do to get their work done, which includes recording the specific steps that they perform or need to perform works pretty well when clients don't provide the requirements or constraints upfront.

I am relatively ignorant on formal engineering, but I do like that you have provided a fairly clear definition, which was "Clearly define the constraints in which your project will operate under and prove that they will hold under those constraints". It is better than the people saying know more math, without saying how, or what, or why it is useful in any clear way, and saying software is math just doesn't cut it.

That is a great counter example. I expect there to be a slow migration to platforms like [this formally verified microkernel](https://sel4.systems/). This will take time and a tremendous amount of effort. But will ultimately address the counter example. In the conclusion of this migration, this puts the SE field into line with the rest of engineering.

Choosing the constraints for a project is no different in the context of CS than the context of any other fields -- electrical, mechanical, etc. It is a conversation, as you stated. This helps in many ways: it helps the developer understand exactly what the client wants, helps the client understand exactly what they are going to get, and helps build an implicit timeline replete with discrete and obvious deliverables and (if done correctly) those deliverables are fairly modular.

Thanks! I, too, get frustrated that people just say 'math! math! math!' That isn't helpful or meaningful. This is a conclusion I came to after talking to quite a few of my friends and colleagues in different engineering disciplines.

Thanks for the information, it is very much appreciated. I was a little frustrated that comments on this thread had people saying you should learn the math and prove your programs but providing no information on how to do so. It would be great if provided resources to show people how to do it. Or even better, provide a project that they worked on and show how they used formal methods to move through the project in detail, which would be wonderful. If someone wants to promote formal methods, then should not just argue for it, but teach it, even a tiny bit. That would get a way better reception.

A little off topic, but it would be great if there was a method/system which could provide requirements tracking down the set of artifacts to where you could point to a bit of source code and say it implements that certain requirement. Sort of like a chain of responsibility for code and associated documents. That might be a pipe dream, I don't know.

Anyway, thanks for the information, I remember seL4 being mentioned in discussion of the sorry state of software on medical devices, but had forgotten it until you mentioned it. Thanks.

To address your specific concerns regarding "learning the maths": that's a bit disingenuous from the people stating it. It is actually logic they are talking about, rooted in the discrete math branch. For seL4 you can actually read the proofs and their conclusions: http://sel4.systems/Info/FAQ/proof.pml. It's a lot of (structural) induction style proofs. That page will be a good starting point and just google around for missing holes as you need.

The current default is for people to work extremely hard and make minimal progress in software. Startups or giants most development is horribly inefficient. So, I don't think there is much to defend about how things actually work in practice.

I agree with this. Anything is better than how its currently done

As far as I've seen, there are generally more inefficient and unsustainable ways of doing anything than efficient and sustainable ways. If this is true, the most likely to occur software implementations are most likely wrong, and making money from these wrong implementations by exploiting their low burden of knowledge and low initial cost serves mostly to create a positive feedback loop of less and less efficient and sustainable software systems. Assuming civilization is going to last and keep using software longer than your own lifespan, this positive feedback loop is a bad thing.

It is a special snowflake because the semantics and correctness of nontrivial programs are often in the eye of the beholder (is Microsoft Word or Google Search 'correct'?). This isn't the case for bridges, cars or toasters. It's not just a matter of adding magic engineering dust until programming is engineering.

You're missing the point though, formal verification ensures that a program hews to a formal specification (proof) which is well-defined and can be reasoned about. Whether the formal specification fits the problem is a different story, but seeing as you can neither prove you understand what the program does nor whether you understand the problem, I think getting one half of that dichotomy is really important to getting the other half.

I don't see how I'm 'missing the point' nor do I have anything against formal methods. They just don't turn programming into engineering - we're a long way from that and some of it has to do (in a completely unglamorous way) with the nature of programming. We just don't know how to turn it into engineering the way bridge-building became engineering.

> They just don't turn programming into engineering

No, what turns programming into engineering is having a rigorous understanding of proof methods and being able to apply them to solve problems the way solid science is used to solve problems in other engineering disciplines. Civil engineering and electrical engineering and mech-e and so on became engineering through the discovery of underlying principles that allowed processes to be formalized, standardized, and improved.

Formal methods have to be at least part of the answer here, unless you can think of a better way to formalize, standardize, and improve the process of software development.

what turns programming into engineering is having a rigorous understanding of proof methods

To believe that, you have to believe that simply adding maths to something turns it into engineering. I think this is fairly obviously not the case.

You literally lopped off the second half of that sentence which does all the work. Of course the part you quoted is not the case, that's why it's not what I said.

You're also misunderstanding me if you think I think "adding maths" to CS will turn it into engineering. We're already doing math! I think CS could be made a lot more solid by being honest that we are doing math and adopting the relevant formalisms that already exist to make reasoning about mathematics easier.

Do you just disagree that that would help, or do you reject the premise that it could be made better entirely?

The thing is that math isn't all that rigorous either. Formal methods (i.e. computer-verified proofs) are still very much the exception. Proofs are written for other humans to consume, and details tend to be glossed over. Usually this is fine, because the readers are mathematicians themselves and can fill in the gaps, but occasionally this leads to a crucial counterexample being overlooked.

Now what does make mathematics slightly more rigorous than other disciplines is the fact that once someone bothers to actually work through the details and finds a counterexample, they can convincingly demonstrate to other mathematicians that the proof is incorrect. Often, the detail in question isn't even all that important, and a workaround can be found that saves the overall proof. But software development is also rigorous in this sense; once you find a case the program handles incorrectly, you can write a testcase to show the difference between expected and actual behavior. And that doesn't usually show the whole program to be misguided, you can just rewrite a small part and things work again.

You seem to want a method that can not only make definitive statements after the fact, but that can actually ensure for almost all programs and almost all desirable properties that the program fulfills the property. But this is actually much more rigorous than most mathematicians ever bother with, and for good reason.

Complete verification requires stating every obvious fact in excruciating detail, because that is the only way to be sure that it is indeed obvious and a fact; in addition to tracking the complex interactions of the whole thing. Most humans really don't want to make this kind of mental effort, if they can avoid it. Even static type annotations are too verbose for some, which has lead most modern languages to include some form of type inference. I don't think you will see widespread adoption of formal methods before proof assistants are developed that can similarly handle most of the simple but tedious tasks, so that humans can focus on the actually important bits.

I actually think dependently-typed languages like Idris are the most promising in this area right now, at least until proof assistants get a lot better.

It's also not specifically the rigor in mathematics, but the grounding in solid principles. They have axioms, they know how to prove things, and they know which proofs to trust and why for the most part. What frustrates me most is stuff like programmers haphazardly reimplementing monads over and over again instead of moving on with what they were actually working on before the language and type system got in their way.

> formal specification

Where did the formal specification come from?

How do I know the formal specification is what I actually wanted?

Is the connection between the informal requirements to the formal specification easier to trace/follow than the connection between the informal requirements and the code?

Code is the formal specification.

There are two separate problems here - one is that you might not be able to clearly explain what you actually want. The other is that you might simply fuck up when writing the formal spec (code). Formal verification is meant to assist you in the latter - when you know what you want, but can make mistakes writing it down, or not realize your description is self-contradictory in some aspects.

> Code is the formal specification.

Yes, people tend to forget that. Having a second formal specification can be helpful, because writing things down multiple times (differently) often helps understanding.

What I've seen so far is that (non-code) formal specs can be very useful when the domain is highly technical, for example network protocols, because they illuminate aspects that are hidden in "production" code.

Of course the fact that important aspects are hidden is a more general problem.

Code is a formal specification. You can have layers of such specifications. The problem with viewing code as the specification is that a lot of languages obscure the intent and only reveal the how.

I'm working on a radio product, it's clear how data is being moved into certain buffers. It's clear when data is moved into certain buffers. It isn't clear why data is moved into certain buffers, or if the code is correct, only that it's being done.

A higher level specification set allows us to have a documented understanding of why the code does what it does, and allows us to reason about it at that level. It also makes it feasible to bring new people into the project, because 150k sloc (not a huge project, but not small) of largely low-level code is not something someone new can jump in on and understand quickly.

We also have something that's much easier to reason about when designing system tests, and to test the code against. We write the tests as though the specification were the reality, and test the code against that model to detect where it diverges. If we only had the code, what would we test it against? If it's its own spec, then it can't be wrong.

No, the correctness is in the eye of a spec. Now, whether companies formally define their specs is a different story. Many startups don't.

With that said, if Microsoft Word meets the given spec, then it's correct. One way to prove this correctness is with testing.

This is the case for bridges as well. If I hand a spec to an engineering firm requesting a bridge from A to B at any given price. Well then, there's a lot of bridges that satisfy those constraints.

Just because many software companies today don't choose to formally specify a spec and prove a programs correctness upon delivery doesn't mean it's a special snowflake. It just means those teams are immature.

Sometimes software development doesn't require a mature team. Like most decisions, there's a cost and timing tradeoff.

The problem with this line of thinking is that the problems that matter are not related to 100% implementing the spec correctly.

The problems that matter are in the design of the spec to begin with. The important part is picking the CORRECT business requirements, NOT in implementing those business requirements correctly.

And do you know what the best way is to test whether you got the spec right? You deploy and see if the feature gets traction.

The "spec" that matters is the success of the business.

And building a product, and releasing it, is the way to formally test if your feature is "correct" according to the spec that is The Market.

>The important part is picking the CORRECT business requirements, NOT in implementing those business requirements correctly.

It's both, though. You also can't tell if you've implemented them correctly if you don't have a formal spec.

Your notion of correct does not apply to everyone: for many of my projects, the implementation that goes against the spec but has higher traction is implemented correctly, and the implementation that follows the spec but has lower traction is implemented incorrectly. The spec is just someone's idea of what will have the highest traction - it doesn't make code that follows it correct.

No, you just don't understand the definition of correctness as it relates to software. Correctness -- like safety -- is formally defined. You might want to look it up.

Not really.

If I make a mistake building my web app, then it will either not matter, or someone will notice the bug in production.

And then when someone notices the bug in production, it can be fixed. If nobody notices it, then I guess it wasn't very important to begin with and can be left "broken".

Implementation bugs are the EASY part, and don't matter a lot of the time.

Or here is a better scenario.

Lets say I am writing a feature, and I think of a way to implement the feature much quicker, but isn't 100% "correct" according to the spec. The quick and dirty, but "incorrect" way to implement it may actually be a better thing to do, because now I can spend my time working on other stuff that is more important.

Purposefully doing the "incorrect" thing according to spec, may actually be the right decision.

Uhm... I was responding to a conversation about software engineering not product development. The two are orthogonal.

You just described the responsibility of a product manager, and finding product-market fit. None of which requires software development. Software development may help but product management certainly doesn't require it.

This is not at all the case.

Product development skills are extremely important for a software engineer to have, especially at smaller companies, because a lot of the time the person making these product decisions IS the engineer.

During my engineering career, most of the time my boss gives me a general goal for a product or feature that needs to be built. And then I take that general idea for a product, and make all the product decisions about what to build and how to build it MYSELF.

At smaller companies there may be NO product manager. Or maybe the product manager is only making very high level decisions, and isn't really involved in every little nitty gritty detail about the product.

You the engineer have to make the product decisions. And you have to balance those product decisions against tradeoffs, such as how long would it take to build, how high quality it is, and other software engineering design tradeoffs.

Product design and software engineering are very closely related, and any good senior engineer should be competent at both. Software engineering makes you better at product design, and vice versa.

Like I said: A may help B or B may help A, does not imply B requires A. Where A = software development; B = product management.

Yes, most startups don't formally define their spec. That's what I've said.

Managing the spec and ensuring product-market fit falls under the domain of a product manager.

So, that's great, you did software development and product management. You wore many hats... like most people do in startups. Doesn't negate the fact that you were a software engineer taking on additional responsibilities.

Trust me, when you work on a team with a clear separation between product management and software engineering and you have a great product manager... it is pure bliss. The only company I've ever felt that technical nirvana with was Google. My god they know what they're doing when it comes to software engineering and separation of responsibilities. At least the team I was on did.

Your job as a software developer is to solve problems with code - not to take the thing someone else designed and make it go. That line of thinking just doesn't work.

Designing and building software are now the same thing. And that is only going to become increasingly true. Designing solutions in the context of modern systems inherently requires intimate knowledge of those systems and the capabilities of the technology being used to solve the problems. The "design/spec/build/test" pipeline is dying.

You can recognise that that's a good thing and get on board or you can be left behind.

Thanks for the laugh.

You misunderstand what a spec is. And you misunderstand what product management is. At no point did I say software engineers aren't responsible for designing and building software. And at no point did I say designing solutions doesn't require intimate knowledge of those systems and capabilities. In fact, that's exactly what I've been saying.

That's what software engineers are there for. To provide expert knowledge and guidance.

But, do you think the electrical engineers defined the spec for One World Trade Center? No they didn't. They got the spec from the architects and they worked to satisfy those requirements.

The spec is not static. There is no design/spec/build/test pipeline in the strictest sense. The spec is dynamic. It's updated through design/spec/build/test iterations.

Just like an electrical engineer may surface new knowledge back to an architect that requires the spec to change... or an electrician in the field will surface new knowledge back to the electrical engineer that requires the spec to change.

Changing the spec is expected. It's called change management.

I don't need to get on board with anything. Google isn't getting left behind anytime soon. And the way they approach software engineering is largely the correct way; I agree with it. (They do however lack coherent product management in some areas.)

But software is the spec. In many cases, if you can formally specify what a function should do, you have already written it.

"But software is the spec."

This whole discussion can be replaced with this sentence.

There are very, very few languages (or few applications of every language) where we can honestly say "software is the spec".

Please tell me, what is the specification of this code so that we can verify and validate it:

  (defun f (x y) (* x y))

Is the specification: `f` shall return the product of two numbers?

Perhaps. Perhaps it was supposed to be addition. Perhaps it was only supposed to apply to integers. If the above spec is correct, is the code correct? Maybe. It doesn't react well when given non-numeric values. Is that a problem? I don't know, the code doesn't explain who is responsible for validating input and who is responsible for handling errors.

A specification is a hybrid prose/formal document that would give us all that information (if it had any value). The code above is not a specification, it is an implementation. No different than a gear or a cog or a lever in mechanical engineering. It is a thing which does some work. We can examine it and see what it does. But we cannot, by observation or execution, determine why without greater context. That context is the specification.

The software is an artifact, one among many, which (hopefully) satisfies a specification.

You're misunderstanding what I mean by spec. A spec is made up of a list of requirements. This list of requirements can be considered constraints on processes, performance, features, limitations, whatever. Whatever makes sense in the world of the specifier.

For example, I can have a requirement that says: "The program shall generate a set of weekly time schedules that are maximally preferable, based upon each students' preferences, for all students at a given location while taking into account resource constraints re: room availability and teacher availability." Of course, this isn't specified to the level of detail I'd put in a real spec, but it serves as an example.

There's many ways to solve this requirement, i.e., there are many different programs that satisfy this spec.

There are two solutions that may stand out: (1) a brute-force approach, and (2) a convex optimization approach.

Since I've not explicitly defined a speed of execution requirement in this spec, then a brute-force approach may make sense... even if it runs for 5 days. In the real-world, you'd confirm this undefined assumption.

If instead my spec said this needs to complete within a day, then maybe the convex approach would make more sense. However, you'd first seek more definition in the spec, i.e., how many students are we generating schedules for? If it's only 10, maybe brute-force, if it's 20k, then convex.

So on and so forth.

Now, the interesting part comes when you create the end-to-end (E2E) and acceptance tests. These tests should be the first thing you write because they follow directly from the spec. They will stand up the program as if it's running in production and drive it as such to test whether it adheres to the spec.

Once all your E2E and acceptance tests are passing, and we've eatablished that your tests cover the spec completely, then we can mark the program as correct with respect to the spec.

There are many different software designs that satisfy a spec.

The software is not the spec.

Thing is, the need to formally define "behaviour" like that is a symptom of poor organisational/team structure. If you have multi-discipline teams with end-to-end accountability for a complete product (or vertical slice of a product) then your "spec" can be replaced with a problem statement and all of a sudden people can start focusing on whether the output solves the problem rather than whether it satisfies some arbitrary behaviour.

It's blindingly obvious that you've never worked in, worked on, or managed a successful large organization (say >500 people || >$1B mkt cap) or a successful large project (say >5k man-hours || >50 people || >$10M budget).

> whether the output solves the problem rather than whether it satisfies some arbitrary behaviour

The spec is considered the solution to the problem! It's not arbitrary in any sense of the word.

Re: first paragraph - incorrect.

The problem with "specs" is that you don't know whether they solve the problem until the solution is implemented and shipped. And even then, you have no real way of knowing what's meat and what's cud. So lots of time, money and people are thrown at solutions that - at best - are wildly bloated or inefficient and - at worst - completely fail to address the actual problem at hand.

The _need_ for specs is - even in large organisations - typically down to misplaced accountability. When you decompose the problem space into small pieces and give development teams a high degree of problem-solving autonomy _and_ accountability for production, the organisational disconnects that lead to the "need" (or, rather, the ill-conceived desire) for burdensome process and specification largely go away.

This isn't witchcraft - it's progress. It works; and it works in large organisations. You haven't witnessed it, so you don't believe me. If/when you do, I'd be willing to bet you'll be converted as I was.

But I'm sure I've given you plenty of reasons to double down on your skepticism.

> Re: first paragraph - incorrect.

Please, do detail.

> The problem with "specs" is that you don't know whether they solve the problem until the solution is implemented and shipped.

No. Good product management eliminates this risk. And that's what you're talking about: risk.

You can test a product, feature, anything, many different ways before you build an actual implementation.

That's basic product and risk management.

> And even then, you have no real way of knowing what's meat and what's cud.

Monitoring.

> When you decompose the problem space into small pieces and give development teams a high degree of problem-solving autonomy _and_ accountability for production

You just like... defined what a spec is... man.

> This isn't witchcraft - it's progress. It works; and it works in large organisations.

Please provide the proof to back this up. Otherwise it's a baselsss claim.

> You haven't witnessed it, so you don't believe me.

No, I've arrived at my beliefs through the data on this point.

And the fact of the matter is that 100+ successful companies that have shipped successful products/projects operate with specs across many different industries from pharmaceuticals to construction to aeronautics and so on and so forth.

If the data supported your conclusion, then I'd agree with it. But the data does not support your conclusion.

I agree with that totally.

Put another way, the problem with having a "software spec" is that you already have the "software which is a spec" and now you have 2 specs.

Or a 3rd way, figuring out the right interface for 2 components is at least 50% of the work when writing software. So, spec writing is like programming. And you wouldn't want to program by committee, would you?

This is one thing Amazon got right - having small internal departments and interacting like separate companies.

Software is not the spec, it's an implementation... of which there are many implementations that satisfy one spec.

Spec writing is not like programming, and if it becomes like programming, then you're doing it wrong.

Specs are meant to constrain the visible solution space by defining the problem sufficiently.

To put it in programming language terms: a spec is declarative not imperative.

I guess you have never heard of declarative programming, design by contract or logical programming, which explicitly does constrain the visible solution space by defining the problem sufficiently.

Though imperative programming looks at the problem from another angle which is closer to execution details, it's not fundamentally different. A smart compiler/interpreter may completely ignore those details as long as it produces the right output, as specified by the spec. That spec being the code.

This is obvious when you see that one style of program can be converted to another style without losing the semantics.

Actually, it is fundamentally different in that just building the thing / just running the experiment is cheaper than doing the simulations or proofs.

Every other discipline does simulations because actually running the experiment is magnitudes more expensive and time consuming.

See "Why software development is an engineering discipline"

    https://www.youtube.com/watch?v=zDEpeWQHtFU

I agree. The primary thing distinguishing software development from other engineering fields is that the cost of building the product is essentially zero. Because building is what your compiler does. What a programmer does is design, and that is always influenced by the constraints of manufacturing - which, for software, are almost non-existent.

So like, for example, Monads. Monads are applicable across every program ever written and with some rules laid out around them have remarkable properties. Comonads too.

Can we use those? By your criteria, I mean.

There may be thousands of typs of programs but how many software design patterns are there? This is a much better analogy I think.

You can't seriously be putting software engineering above civil or mechanical engineering... They're two completely different fields which both require years and years of training.

Wouldn't it be more fair to compare the bridge types to for loops?

You need science to come up with it and engineering to apply it in practice.

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