mypy VS go

It's got type annotations and mypy has a discussion about it here as well: https://github.com/python/mypy/issues/1282

There is already an AOT compiler for Python: Nuitka[0]. But I don't think it's much faster.

And then there is mypyc[1] which uses mypy's static type annotations but is only slightly faster.

And various other compilers like Numba and Cython that work with specialized dialects of Python to achieve better results, but then it's not quite Python anymore.

[0] https://nuitka.net/

[1] https://github.com/python/mypy/tree/master/mypyc

In Python there is MyPy that can help with this. https://www.mypy-lang.org/

It's funny you should say this.

Reading this article prompted me to future-proof a program I maintain for fun that deals with time; it had one use of utcnow, which I fixed.

And then I tripped over a runtime type problem in an unrelated area of the code, despite the code being green under "mypy --strict". (and "100% coverage" from tests, except this particular exception only occured in a "# pragma: no-cover" codepath so it wasn't actually covered)

It turns out that because of some core decisions about how datetime objects work, `datetime.date.today() < datetime.datetime.now()` type-checks but gives a TypeError at runtime. Oops. (cause discussed at length in https://github.com/python/mypy/issues/9015 but without action for 3 years)

One solution is apparently to use `datetype` for type annotations (while continuing to use `datetime` objects at runtime): https://github.com/glyph/DateType

PEP 695 is great. I've been using mypy every day at work in last couple years or so with very strict parameters (no any type etc) and I have experience writing real life programs with Rust, Agda, and some Haskell before, so I'm familiar with strict type systems. I'm sure many will disagree with me but these are my very honest opinions as a professional who uses Python types every day:

* Some types are better than no types. I love Python types, and I consider them required. Even if they're not type-checked they're better than no types. If they're type-checked it's even better. If things are typed properly (no any etc) and type-checked that's even better. And so on...

* Having said this, Python's type system as checked by mypy feels like a toy type system. It's very easy to fool it, and you need to be careful so that type-checking actually fails badly formed programs.

* The biggest issue I face are exceptions. Community discussed this many times [1] [2] and the overall consensus is to not check exceptions. I personally disagree as if you have a Python program that's meticulously typed and type-checked exceptions still cause bad states and since Python code uses exceptions liberally, it's pretty easy to accidentally go to a bad state. E.g. in the linked github issue JukkaL (developer) claims checking things like "KeyError" will create too many false positives, I strongly disagree. If a function can realistically raise a "KeyError" the program should be properly written to accept this at some level otherwise something that returns type T but 0.01% of the time raises "KeyError" should actually be typed "Raises[T, KeyError]".

* PEP 695 will help because typing things particularly is very helpful. Often you want to pass bunch of Ts around but since this is impractical some devs resort to passing "dict[str, Any]"s around and thus things type-check but you still get "KeyError" left and right. It's better to have "SomeStructure[T]" types with "T" as your custom data type (whether dataclass, or pydantic, or traditional class) so that type system has more opportunities to reject bad programs.

* Overall, I'm personally very optimistic about the future of types in Python!

[1] https://github.com/python/mypy/issues/1773

# is fixed: https://github.com/python/mypy/issues/12987.

You probably already know but you can add type hints and then check for consistency with https://github.com/python/mypy in python.

Modern Python with things like https://learnpython.com/blog/python-match-case-statement/ + mypy + Ruff for linting https://github.com/astral-sh/ruff can get pretty good results.

I found typed dataclasses (https://docs.python.org/3/library/dataclasses.html) in python using mypy to give me really high confidence when building data representations.

Make sure you have Go installed https://go.dev/.

The Go Programming Language

When Go first shipped, it was already well-documented that the only stable ABI on some platforms was via dynamic libraries (such as libc) provided by said platforms. Go knowingly and deliberately ignored this on the assumption that they can get away with it. And then this happened:

https://github.com/golang/go/issues/16606

If that's not "getting burned", I don't know what is. "Trying to provide a nice feature" is an excuse, and it can be argued that it is a valid one, but nevertheless they knew that they were using an unstable ABI that could be pulled out from under them at any moment, and decided that it's worth the risk. I don't see what that has to do with "not being as broadly compatible as they had hoped", since it was all known well in advance.

Sadly, I think that is indeed radically different from Go’s design. Go lacks anything like sum types, and proposals to add them to the language have revealed deep issues that have stalled any development. See https://github.com/golang/go/issues/57644

I've been writing a lot about Go and gRPC lately:

I have a mountain of respect for Bell Labs and its contributions to the public welfare, and a lot of respect for the current group of alumni, mostly at Google, and mostly affiliated to a greater or lesser degree with golang. I have my differences with one or two of them (Pike telegraphs a wildly overcompensated imposter syndrome, but he’s almost as much of a genius as he acts like he is and who am I to judge on an overcompensated imposter syndrome, moreover when the guy in at the next desk over is Ken Thompson, who wouldn’t be a little intimidated by the legend).

With that said, golang is too opinionated for its level of adoption, too out-of-touch with emerging consensus (and I’m being generous with “emerging” here, the Either monad is more than an emerging consensus around the right default for error handling), and too insular a leadership to be, in my personal opinion, a key contender outside some narrow niches.

I’m aware that there are avid advocates for golang on HN, and that I’m liable to upset some of them by saying so, so I’m going to use some examples to illustrate my point and to illustrate that I’ve done my homework before being critical.

Many, including myself, became aware of what is now called golang via this presentation at Google in 2007 (https://youtu.be/hB05UFqOtFA) introducing Newsqueak, a language Pike was pushing back in the mid-90s with what seems to be limited enthusiasm no greater than the enthusiasm for its predecessor Squeak. Any golang hacker will immediately recognize the language taking shape on the slides.

I’ve been dabbling with golang for something like a decade now, because I really want to like it. But like a lot of the late labs stuff it seems to have suffered from the dangerous combination of the implications of Richard Gabriel’s Worse is Better observation: it was simpler, faster, cheaper, and ultimately more successful to incrementally adapt innovations from Plan9 into Linux (and other Unices), to adapt innovations from sam and acme into nvim/emacs (and now VSCode), and to adapt channel-based and other principled concurrency from Newsqueak/golang (not to mention Erlang and other more full-throated endorsements of that region of the design space) into now countless other languages ranging from things like TypeScript and Rust at the high end of adoption all the way to things like Haskell at more moderate levels of adoption. Ironically enough, the success of UTF-8 (a compromise for the non-ASCII world but the compromise that made it happen at all) is this same principle in action via the same folks!

And golang would be fine as yet another interesting language serving as a testbed for more pragmatic applications of radical ideas: but it’s got corporate sponsorship that puts Sun Microsystems and Java to shame in scale and scope, but done quietly enough to not set off the same alarm bells.

The best example of this is probably this GitHub issue: https://github.com/golang/go/issues/19991 (though there are countless like it). I’ve worked with Tony Arcieri, he’s brilliant and humble and hard-working and while we haven’t kept in touch, I keep an eye out, and he’s clearly passionate about the success of golang. But proposal after proposal for some variation of the Either monad has died on procedural grounds for nearly a decade, all while being about the only thing that everyone else agrees on in modern industrial PLT: TypeScript supports it, Rust supports it, C++ de-facto supports it via things like abseil and folly, and of course the hard-core functional community never even bothered with something worse in the modern era. You can even kind of do it, but there are intentional limitations in the way generics get handled across compilation units to ensure it never gets adopted as a community-driven initiative. Try if you don’t believe me (my golang code has a Result type via emacs lisp I wrote).

Another example is the really weird compilation chain: countless serious people have weighed in here, I’ll elide all the classics because most people making these arguments have their own favorite language and they’ve all been on HN dozens of times, but a custom assembly language is a weird thing to have done, almost no one outside the hardcore golang community thinks it’s sane, the problems is creates for build systems and FFI and just everything about actually running the stuff are completely unnecessary: there are other IRs, not all of them are LLVM IR if you’ve got some beef with LLVM IR, and given that go doesn’t seriously target FFI as more than a weird black sheep (cgo) there’s, ya know, assembly language. It’s a parting shot from the Plan9 diehards with the industrial clout to make it stick.

The garbage collection story is getting better but it’s an acknowledged handicap in a MxN threading model context, it’s not a secret or controversial even among the maintainers. See the famous “Two Knobs” talk.

Raw pointers, sum types, dependency management, build, generics that never get there, FFI: solved problem after solved problem killed by pocket veto, explained away, minimized, all with mega-bucks, quiet as a gopher corporate sponsorship fighting a Cold War against Sun and the JVM that doesn’t exist anymore marketed by appealing to the worst instincts of otherwise unimpeachable luminaries of computing.

There is great software written in golang by engineers I aspire to as role models (TailScale and Brad respectively as maybe the best example). I had to get serious about learning golang and how to work around its ideologically-motivated own-goals because I got serious about WebRTC and Pion (another great piece of software). But it sucks. I dread working on that part of the stack.

Go enums do suck, but that’s because we pay a very heavy price for golang being mainstream at all: we’ve thrown away ZooKeeper and engineer-millennia of garbage-collector work and countless other treasures, it sucks oxygen out of the room on more plausible C successors like D and Jai and Nim and Zig and V and (it pains me to admit but it’s true) Rust.

Yes there is great software in golang, tons of it. Yes there are iconic legends who are passionate about it, yes it brought new stuff to the party and the mainstream.

But the cost was too high.

It seems to be userspace accessible: https://github.com/golang/go/issues/66450

Something you should keep in mind regarding maps in Go. They don't shrink after elements are deleted runtime: shrink map as elements are deleted #20135