Everything you said is from the perspective on being not only in a Haskell job but in a Haskell team. Your 3 months is 5 years for someone trying to learn on their own in their spare time. And then they need this to get a Haskell job due to the competition for such job and the queue of super smart people lining up for a Haskell job. And the pay cuts are brutal. Now you are an outlier, working on a Haskell team for Google, the rare triad of using Haskell at work, presumably being well paid, and having that mentorship from other team members.
> After 6 years of industrial Haskell, I know nothing about category theory. It has not prevented me from using web frameworks.
As someone in as Haskell team, maybe this is possible. You don't have to try and pick apart the online knowledge. For example a lot of libraries use Lens. I want to understand Lens? It is not simple: check out the diagram on https://hackage.haskell.org/package/lens. "Yeah but it's just X Y Z". Great - I've been to many FP meetups, and seen a lot of stuff online and there is no simple help for this stuff.
You're making it seem harder that it really is. Yes, it's hard if the package documentation is all you have, but that's the hard way to learn. There are other online unofficial documentation and tutorials (of diverse quality). There's also a book (https://leanpub.com/optics-by-example) that I find adequate for a reasonable learning experience (I think I would have saved much time if I had started learning lens using this book.). And, you don't need to know the entire lens package to use it. The most commonly used part of lens (Lens proper, not Prisms, Isos, etc) is only a small fraction of the whole thing.
You can skip the theory and go straight to usage: https://www.youtube.com/watch?v=QZy4Yml3LTY
I learned the key parts of Haskell in 3 months of my spare time from university (where I had much less spare time than I have now in industry). And that was at a time where learning Haskell was much harder than it is now; today there are a lot of really detailed books, tutorials, and videos available, tooling works out of the box with few surprises, and error messsages are way better.
Of course learning in your spare time does not give you as much practical experience and feedback as you get on a job, but it gets you enough to get into such a job.
> You don't have to try and pick apart the online knowledge.
Not any more.
* Step 1, buy a beginner book and work through it.
* Step 2, work through FP Complete's [1] Applied Haskell Syllabus (https://www.fpcomplete.com/haskell/syllabus/). This will make you comfortable with most day-to-day data structures, techniques, testing, benchmarking and so on.
* Step 3, practice building some small applications that you think companies will actually need. Web servers, input validation, streaming data processing, and so on. It doesn't have to be fancy or use "cool" techniques, it just has to be /useful/.
* Optional Step 4, for extra hireability: Become better-than-average in a specific topic. This could be testing, performance, developer tooling, documentation, web stuff, anything that gets your juices flowing. Do a bit of open-source work in that area. Go to some meetups or conferences to see who's hiring, what they are doing, and what might be useful for them
> I want to understand Lens?
Again, you don't need to do that to get a job. I've conducted ~ 40 technical interviews for filling Haskell positions for various companies, and none required this. What is required is that you can do normal /useful/ things, with the high amount of correctness, clarity, refactorability, and reliability that Haskell provides.
Haskell, like mathematics, knitting, and C++, offers near infinite avenues of special topics that you can deep-dive into if you want. People talk about those at meetups because they excite them. But you don't have to do that to build useful software or get a job.
[1] This is the consulting company as part of which I gave most of aforementioned training. It makes most of the training material publicly available.
I think it is quite common, even for people who want to understand things at a fundamental level, to just use stuff without said understanding.
(If you don’t want to go into how plastics are made, &c — but that stretches the metaphor way too far)
with rust, by contrast, which is ostensibly much less general purpose and hasn't been around as long there's already quite a collection and it's easy to see why it was chosen for those things.
Haskell jobs do exist, I have one of them. The big problem is that there are more people who want to do those jobs than there are jobs, so they seem very scarce.
But anyway there are also a number of investment banks I have heard that use Haskell as their “secret weapon” and do not advertise it, in fact those who could speak to details are all under NDA.
Personally I am hoping to help with this issue by building cool open source things in Haskell (and purescript)
I was skeptical for years for all the reasons you said, but I finally decided to set my skepticism aside and see for myself, and oh boy is Haskell great. It has a lot of problems, but I consider myself at least 2x more productive in Haskell.
Both Standard Chartered and Barclays loudly advertise that they use Haskell.
A quick web search turns up their job offers on Reddit, and both also send people to conferences such as Haskell eXchange, to talk about their team tasks, structure, and size. Example: [1]
Their code bases were discussed on HN before, e.g. [2].
Standard Chartered also funded the development of GHCs low-latency, non-stop-the-world, incremental GC, for 2 years until it was recently released [3].
[1] https://skillsmatter.com/skillscasts/9098-haskell-in-the-lar...
[2] https://news.ycombinator.com/item?id=13073605
[3] https://www.well-typed.com/blog/2019/10/nonmoving-gc-merge/
For stuff that doesn't require that runtime (as convenient as it is) they just use familiar old lazy GHC. My understanding is that they are progressively moving more and more to GHC, although my knowledge is five years out of date.
A genuine one. I remember a presentation by a bank about their use of Haskell, and wasn't sure if it was Standard Chartered. I remember they had the subset, and mentioned they basically had to a lot from scratch to interface with various systems.
And now that I have the name, I found a link to someone's copy: https://dshevchenko.biz/hs-research/Haskell-in-the-Large.pdf (used to be available at code.haskell.org). My recollection of the paper isn't perfect :)
> My understanding is that they are progressively moving more and more to GHC, although my knowledge is five years out of date.
Ah, thank you!
I remember hearing this said about Perl back in the day! Language X is so awesome businesses use it in secret because they don't want their competitors to discover the secret to their success.
Not saying it couldn't happen, but you can say it about any language and it can't really be disproven.
This is why we need more publicity-visible Haskell success stories.
Really the thing that convinced me to really dig into haskell was that there were so many things that I wanted to learn but so much of the extra information had roots in haskell topics. So i basically said "to achieve my goals I need to know haskell even if i never use it for anything practical".
Slowly, as I learned more, I realized it is great. I wish I had chosen to learn haskell 10 years ago instead of like two years ago.
There are plenty of cases where a broken notebook is about as good as a spreadsheet, and languages suited/typical to that use have a psychological victory that results in apples to oranges comparisons.
I think the difficulty of Haskell is overrated. It's just different. The crowd who complain about Haskell being hard despite x years experience are the same people who speak English and think Mandarin is hard.
And yet 1.7+ billion people speak Mandarin, and most linguists agree that English is actually the harder language owing to its more branched roots.
Haskell is what happens when you go full lambda calculus, and the dedication to referential transparency really forces you down some interesting paths/abstractions. It's also worth noting that other functional languages like OCaml and lisp do not force purity so the idioms are not as extreme.
The impedance mismatch essentially boils down to Turing Machine vs Lambda Calculus and as such you don't find many familiar friends when switching camp (to begin with, at least!) The Haskell idioms are very different and the consequences of referential transparency ripple throughout the way you need to think about computation.
It's also worth noting that Haskell is a language laid bare - much of the features and abstractions are plain-old functions which means you can "just" duck into them, implement them for yourself or read them as libraries. But what we often forget is all the abstractions we needed to learn when grokking "programming" (which was probably imperative style programming) the first time round. Most people have moved on from the time when trying to conceptualise what an object is or how methods work or even working with mutable state. When you get to design patterns - some of the implementations are quite complex the first time round. Eg the visitor pattern/double dispatch is not particularly simple when you sit down and manually expand the execution of those calls and yet when you use it, it's quite simple.
When we program with objects, most of us don't stop to think about vtables anymore* we just use the object to solve our immediate problem.
The more I see of Haskell, the more confident I am that it just uses a very different set of abstractions that you can just use and forget about except you get the benefit of a HM type system and referentially transparent code. It's also nice that that itself somewhat forces you towards a more functional-core imperative style architecture where your business logic is pure and mostly happy path code and your boundary is a bunch of monad imperative glue.
I think at the end of the day FP makes the hard things easy and the easy things hard. But as the Turing Machine and Lambda Calculus are equivalent then being adept at both schools is like having twice the arsenal for dealing with a given problem.
*naturally when performance becomes a problem you start to unravel abstractions.
Clojure does, in some degree.
But clojure is very strictly imperative. Atoms are easily accessible in the stdlib and side effects can be called inline and hidden within functions. This masks IO from a perceived return type.
Haskell differs here because it forces you down the path of "everything explicit" and "everything referentially transparent". Essentially monads emerge as a result of this, but their use definitely feels unergonomic in clojure
Compare that to Erlang's half a day to a day for onboarding, and one to two weeks before pushing stuff to prod.
I can't imagine any company that could afford three full-time weeks of onboarding.
> investing 3 months for life-long increased productivity (even if it's just a few percentage points; most feel the effect is larger)
The tales of increased productivity are purely anecdotal. Especially if you're talking about a few percentage points.
Erlang's a half day for onboarding if you're onboarding a Haskell programmer, not because Haskell programmers are that awesome but because they've already had to learn the hard things involved in Erlang to work with Haskell [1]. Otherwise, that's ludicrous nonsense. Most programmers will need several hours just to figure out how to write the equivalent of lists:map in the new Erlang, immutable world, more hours to figure out how to write things non-trivially with it, and a good couple of weeks at a bare minimum to figure out how to structure applications in an OTP world, then some more time to figure out how to debug it.
It's not especially harder than learning SQL or the latest Javascript framework or other things that aren't Algol-descended languages, but it's nowhere near that easy.
[1] I went the other way. I found Erlang an excellent introduction to Haskell; you get to absorb some of the challenges like working in pervasive immutability in an environment where you're not also swallowing a complicated type system or strict effects separation.
Oh yes. Months even. Routinely.
I was in a Haskell team at Google, and have trained groups at various companies professionally. From that experience, for a normal developer with working experience in Java, Python, or C++:
* It takes 2-3 weeks of full-time onboarding (half with a coach, half self-study) to work on a typical industrial Haskell project.
* It takes around 3 months of full-time participation in such a project to know a wide array of libraries and feel ready to tackle almost anything.
The companies involved were happy to make this time investment for increased productivity over the time they expected their employees to stay with them.
On an individual level, it makes sense that if you're just getting into programming, and you have the choice between investing 2 weeks into Python to be productive, or 3 months for Haskell, you pick Python. It's rational. But after you've been in it for a few years, and you realise you want to do it for another 40 years, investing 3 months for life-long increased productivity (even if it's just a few percentage points; most feel the effect is larger) suddenly becomes a great deal.
Counter point on "complex topics":
After 6 years of industrial Haskell, I know nothing about category theory. It has not prevented me from using web frameworks.