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I wasn't really trying to convince anyone to use Haskell at their day job: I am just a college student, after all, so I would have no idea what I was talking about!

I wrote the article a while ago after being frustrated using a bunch of Go and Python at an internship. Often I really wanted simple algebraic data types and pattern-matching, but when I looked up why Go didn't have them I saw a lot of justifications that amounted to "functional features are too complex and we're making a simple language. Haskell is notoriously complex". In my opinion, the `res, err := fun(); if err != nil` (for example) pattern was much more complex than the alternative with pattern-matching. So I wanted to write an article demonstrating that, while Haskell has a lot of out-there stuff in it, there's a bunch of simple ideas which really shouldn't be missing from any modern general-purpose language.

As to why I used a binary tree as the example, I thought it was pretty self-contained, and I find skew heaps quite interesting.




> > functional features are too complex and we're making a simple language. Haskell is notoriously complex

This is a true statement. (Opinion yada objective yada experience yada)

> In my opinion, the `res, err := fun(); if err != nil` (for example) pattern was much more complex than the alternative with pattern-matching.

This is also a true statement. (yada yada)

The insight I think you're missing is this piece right here: `we're making a simple language`. Their goal is not necessarily to make simple application code. That's your job, and you start that process by selecting your tools.

For certain tasks, pattern matching is a godsend. I'm usually very happy to have it available to me when it is. And I do often curse not having it available in other languages to be honest.

But Go users typically have different criteria for what makes simple/reliable/maintainable/debugable/"good" code than Haskell users have. Which is why the two languages are selected by different groups of people handling different tasks. You're making a tradeoff between features and limitations of various languages.

And the language designers have an even different criteria for those things. In this case, adding pattern matching would absolutely make the language itself more complex, and they apparently don't believe that language complexity is worth the benefits of pattern matching. I think that's a perfectly reasonable stance to take.


I'm not sure if I understand you: the `res, err := fun(); if err != nil` pattern shows up everywhere in most Go code, and I think that pattern-matching would be a better fit for it. Swift does it pretty well, as does Rust, both of which occupy a similar space to Go.

I get that there's a tradeoff with including certain features, I suppose I disagree that the tradeoff is a negative one when it comes to things as simple as pattern-matching, and I think it should be included in languages like Go.


I'm not arguing against pattern matching. Like I said, I prefer it where possible. I'm also not arguing in favor of multiple return with mandatory checked err values. (Though I prefer either over the collective insanity that went into making exceptions the default approach to handling errors in most languages.) I'm just pointing out that I think you're missing a key word in the stance of the go language developers.

They're not saying that if err != nil is better or worse, simpler or more complex, etc... than pattern matching for application code.

They're saying that supporting pattern matching makes the language itself more complex, and they're not in favor of that tradeoff. You're focusing on application complexity, and that's a very different thing.

Both the go language authors as well as the kind of developers that choose to use go think of the relative simplicity of the language itself as a feature. Even if it causes the application code to be slightly more complex. It's just another dimension that can be used when comparing programming languages, and one that group tends to value more than other groups.


Oh ok, I understand. I don't really buy the idea that go is a simple language, I have to say. A lot of go's design choices read (to me) as needlessly complex, like features were added to address corner cases one by one instead of implementing the fundamental feature in the first place. "Multiple return values" instead of tuples; several weird variations on the c-style for-loop; special-cased nil values instead of `Maybe` or `Optional`; `interface {}` and special in-built types instead of generics, etc. ADTs and pattern-matching would obviate "multiple return values", nils, and greatly simplify error handling.


A very instructive exercise for anyone who is or intends to be a software developer is to write some sort of interpreter and/or compiler. (As well as a virtual machine and/or emulator) Depending on your approach this can take a weekend, a few months, or the rest of your life.

For instance, and amusingly enough written in golang, one of the most respected recent books on this topic is `Writing an Interpreter in Go` and its sequel `Writing a Compiler in Go`. https://interpreterbook.com/ and https://compilerbook.com/ Both of these books are reasonably short, and have the reader make meaningful progress within a weekend.

Going through the motions of actually making your own programming language (or reimplementing an existing one) teaches you a lot of things you wouldn't otherwise expect about how to write general code, how to use existing languages effectively, and how things work under the hood. It's also one of the best ways to really get a practical feel for how to approach unit testing.

It's an exercise I'd recommend if you haven't gone through it already. It might make it really click for you why some features that seem like a no brainer and should be in every language aren't, and why some undesirable "features" are so prevalent.


> It might make it really click for you why some features that seem like a no brainer and should be in every language aren't, and why some undesirable "features" are so prevalent.

I hate this kind of "I have secret knowledge, why don't you spend T amount of your time on some big project to maybe come to the same secret insights I mean". If you have an opinion on why pattern matching is so complex and undesirable, just come out and say it please. Otherwise I'll just call you out as not really having an argument.


> I have secret knowledge, why don't you spend T amount of your time on some big project to maybe come to the same secret insights I mean

Alternate interpretation, I learned something valuable from doing this thing, perhaps you'd be interested in doing so as well since the book that took months or years to write will do a better job teaching it than I will in a five minute break while typing on HN.

It's always impressive when freely sharing knowledge and tips is somehow taken as being insular and exclusive.

> If you have an opinion on why pattern matching is so complex and undesirable

Where did I say pattern matching is undesirable? It sounds more like you just want a fight here.

Remember the HN guidelines:

> Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith.


> It's always impressive when freely sharing knowledge and tips is somehow taken as being insular and exclusive.

But you didn't share knowledge. You suggested that you had knowledge that was pertinent to the topic at hand. But you didn't share it. You did share tips for resources where one can learn more, and that's great. But you didn't add something like "... and that's where I learned that pattern matching is undesirable because <technical reason>".

> Where did I say pattern matching is undesirable?

This whole thread was about you saying that pattern matching was undesirable from the point of view of Go's designers or implementors due to their design goal of simplicity. Then you mentioned those compiler resources. The only reasonable interperetation for me is that you wanted to say that you did indeed know concrete technical reasons why pattern matching in Go would be complicated and therefore undesirable.


> This whole thread was about you saying that pattern matching was undesirable from the point of view of Go's designers or implementors due to their design goal of simplicity.

The only use of "undesirable" in any of my comments was in regard to features that are prevalent across languages today. If you must know I was thinking of inheritance and exceptions specifically.

As far as pattern matching goes, I was making no arguments except to say that I like it, adding a feature like pattern matching adds some non-zero amount of complexity, and that the go authors are apparently uncomfortable with that complexity. As I am not a go author, I am unsure of their exact reasoning and would not think to say why they believe that. My implication was not that I have an exact concrete reason for why the go authors feel the way they do. It was merely that I don't inherently disbelieve them when they say they have a reason.

In fact my exact wording was "I think that's a perfectly reasonable stance to take", which does not imply agreement, only a lack of strong disagreement. In other words I don't think they're ignorant of the matter or misrepresenting the situation.

> But you didn't share knowledge. You suggested that you had knowledge that was pertinent to the topic at hand. But you didn't share it. You did share tips for resources where one can learn more, and that's great. But you didn't add something like "... and that's where I learned that pattern matching is undesirable because <technical reason>".

The comment that appears to have gotten you riled up was after the person I was talking to saying they understood. After a discussion about language complexity I thought that it would be appropriate to suggest some resources on a "quick" project that can help build an intuition on that topic. And to be honest, it's a project I like to find excuses to suggest. I find people tend to be surprised at how easy and fun it can be to make some meaningful progress.

I understand that you would like for me to somehow short circuit that process, but I don't believe I am capable of building someone else's intuition by posting a throwaway comment on HN. Intuitions are typically built on experience and tinkering, not reading someone else's experiences.

That you view that project suggestion as a continued argument is unfortunate, I can assure you that was not my intent. Again referencing the HN guidelines, I encourage you in future to try to read people's posts first with the assumption that they are being genuine and only fall back to an assumption of malice when you absolutely have to. Long drawn out arguments over semantics don't help anyone.


Ah... in religion we call that "gnosticism". (Not really important, it just struck me as something weird to find in a HN thread.)


> A very instructive exercise for anyone who is or intends to be a software developer is to write some sort of interpreter and/or compiler.

Another exercise, perhaps less demanding in this regard, is to explore using Free Monads[0] to implement an EDSL[1] for a problem domain. Of course, the approachability of this varies based on the person involved.

> For instance, and amusingly enough written in golang, one of the most respected recent books on this topic is `Writing an Interpreter in Go` and its sequel `Writing a Compiler in Go`.

Queue obligatory reference to "the dragon book":

  Compilers: Principles, Techniques, and Tools[2]
0 - https://softwareengineering.stackexchange.com/questions/2427...

1 - https://www.quora.com/What-is-an-embedded-domain-specific-la...

2 - https://suif.stanford.edu/dragonbook/


Yeah I'm definitely not saying anything bad about the Dragon book here.

But I know there's a recency bias when people are evaluating tech books, so if there's a good book from the last five years I'll recommend that over a great book from the last 15, just so there's a higher chance of the recommendation actually being used.


No worries mate.

I mentioned the dragon book by obligation, not in comparison to the works you referenced.


If anyone is curious about an updated resource, I've found Modern Compiler Design much more approachable than the Dragon Book: Published in 2012, it includes chapters on designing object-oriented, functional, and logical compilers.

https://www.springer.com/gp/book/9781461446989


Hadn't heard about that one, thanks!


one of the most respected recent books on this topic is `Writing an Interpreter in Go`

Is 'recent' the key word here? ;) cause that is a very bold claim to make.



> Multiple return values instead of tuples

I remember having some bugs in Python due to one element tuples, I don't think I would have had the same issue if Python had multiple return value instead..


You keep missing the point entirely. Go was created to solve a very specific Google scenario: offer a valid alternative to C++ and Java for whatever they do in Google. It's not a language created to make college students or language hippies happy..if you are looking for that look somewhere else. Go can be picked up by any dev with minimal experience in C/C++/Java in 1-2 weeks and that was one the main design targets. Another one was fast compile times, adding all those nice features you'd like would also make the language more complex to parse and compile. I think you can talk about how much you like Haskell all day long, but if you keep using Go as a comparison you simply show you have no clue of what you are talking about. It's literally apples to oranges.


Maybe I am missing the point! It certainly wouldn't be the first time in an argument about programming languages.

I do understand, though, that the purpose of Go is not necessarily to push the boundaries of language design. I also understand that it's important the language is easy to pick up, compiles quickly, etc.

I think that some of Go's design decisions are bad, even with those stated goals in mind. Again, I don't want to overstate my experience or knowledge of language design (although I do know a little about Google's attitude towards Go, since that's where I spent my internship learning it), but some features (like "multiple return values" instead of tuples) seem to me to be just bad. Tuples are more familiar to a broader range of programmers, aren't a strange special case, are extremely useful, and have a straightforward implementation. Also, I don't want a bunch of fancy features added to Go: ideally several features would be removed, in favour of simpler, more straightforward ones.


I do agree, I would prefer tuples to multiple return in go.

Perhaps they find it easier to teach to users coming from languages with less or no type inference? Java and C++ programmers in my experience don't tend to be familiar with tuples, despite there being a tuple in the C++ stdlib. My purely uninformed guess is that it's because of how verbose declarations can get in Java, or in C++ without auto/decltype from C++11.




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