1. 3

    When you have a type error, and you always get a type error, the question is whether you get it from QA or your users or your compiler.

    is really good.

    1. 26

      I love it.

      Low-level programming is so often filled with arrogance: Stuff like “I work on hard low level things, only above-average programmers like me can do it”. Don’t believe me? This is literally one of the first pages you read on the Os dev wiki: https://wiki.osdev.org/Required_Knowledge

      In fact, writing an OS is usually considered the most difficult programming task. You will need above-average programming skills before even considering a project like this. Failure to comply will make you look silly.

      ugh. “Failure to comply will make you look silly” Did a 7 year old write this? We don’t want to be taunting beginners or making them feel stupid, we want to be empowering them.

      And that’s the position Rust is taking: Rust helps anyone be a systems programmer. Maybe systems programing isn’t particularly well defined, but many people reading this will think “scary part of programming” and then “oh wait, Rust let’s me do that”. That’s awesome: A clear path forward to doing something scary.

      Lastly, I really do like the design. That’s obviously personal preference though, what I really like is that there is design at all. Again low level programming is littered with bad design or lack thereof: having put work into their design is another way of being more inclusive.

      1. 12

        Low-level programming is so often filled with arrogance: Stuff like “I work on hard low level things, only above-average programmers like me can do it”.

        At a previous workplace, there was a cohort of strong systems programmers who would emphasize the difficulty and attainability of systems programming skills. It was out in the open - this is hard, you can do it, with practice, let’s work on it together.

        This was accompanied with a culture of regular talks, sharing of projects, ideas, workshops to get all devs interested in systems ideas - building a shell, using flamegraphs, writing data structures, cache locality. Frontend, SRE, sysadmins, everybody was welcome. That was real great stuff, the opposite of the more common “hey, Joe Frontend, get out of here and go bang some legos together.”

        Anyway, not sure where I’m going with this - I guess my point is:

        “Systems programming is hard - if you’re willing, you can do it. Here’s some resources” is a more welcome attitude vs. “Let’s scare off these morons”.

        Who knows, one of those morons might get motivated, do some learning, and become a good systems programmer some day.

        1. -9

          Writing an operating system is an enormously difficult task. Scaring off people that are not ready to even begin, that so lack the fundamentally required skills that they can’t even follow basic tutorials? That’s a service to the community.

          It’s simply not the case that everyone can be a systems programmer. Rust is an extremely complicated language, and if someone can’t do systems programming in C they certainly won’t be able to do it in the much more complex language Rust.

          Systems programming is complicated and scary and difficult and it should be. People should be scared to release low level software, because of the massive implications of them getting that software wrong.

          Certainly we do not want to be ‘empowering’ people.

          1. 22

            Writing an operating system is an enormously difficult task.

            Writing an operating system is an enormously large task. It’s not obvious the problems posed by OSs are substantially harder than those posed by distributed systems, compilers, machine learning, UI design, game development, sys ops, etc. Certainly there is much worse tooling for os development! (Rust is one foray into making this better!) Part of the reason, I think, the tooling is bad is because there’s this notion that writing an operating system should be hard: it’s a self-fulfilling prophecy.

            Scaring off people that are not ready to even begin, that so lack the fundamentally required skills that they can’t even follow basic tutorials? That’s a service to the community.

            I am all for giving people basic tutorials! Scaring people, on the other hand, seems like the community is trying to weed out the weak and let only the best programmers in. That’s certainly a possible goal for a community, just not a community I want to be a part of.

            Rust is an extremely complicated language, and if someone can’t do systems programming in C they certainly won’t be able to do it in the much more complex language Rust.

            I guess we’ll see about that! Rust is making the claim that it’s easier to do systems programming in Rust than it is in C.

            Certainly we do not want to be ‘empowering’ people.

            I do :)

            1. 18

              Multiple universities offer a “write an operating system” class in the CS1XX level.

              1. 4

                I couldn’t disagree more, and one of my favorite things about the rust community is how we reject gatekeeping like this. Portraying it as a binary choice a la “either we deter people or they will write bad systems code” is intellectually dishonest at best. As @sevagh noted, it’s possible to both acknowledge the difficulty of writing good low-level code AND encourage people to learn how to do it. Providing good tools, good documentation, good learning resources, and good mentorship is, in my opinion, the best way to accomplish this, and that’s what I see the rust community pursuing

            1. 9

              cf Ponylang for an implementation of this model: https://tutorial.ponylang.io/capabilities/

              1. 7

                Pony also has capabilities on external resources. For example, you need a capability to open a socket.

                1. 3

                  This seems very similar to Rust’s borrowing model, and both of these are excellent!

                  However, capabilities with regards to variables is only one part of the picture.

                  I very much want my programs to be capability safe in terms of external resources too: the filesystem, exec, network access, etc. Functions and modules which require access to these would need to be provided them in order to utilize it.

                  Monte implements this and has interesting demonstrations like https://monte.readthedocs.io/en/latest/taste.html#cooperation-without-vulerability which can safely eval() code from the internet. It doesn’t prevent an abusive user from using all the RAM or all the CPU, but it is impossible for the abusive user to read RAM, write to the FS, send spam emails, etc.

                  EDIT 1 Additionally, capability safety doesn’t even have to apply to a single program! TahoeLAFS is a capability-safe networked filesystem.

                1. 4

                  Then you just print the QR code and then securely delete it.

                  Then microwave the printer.

                  1. 7

                    If you’re afraid of the printer, you still can draw it by hand (can take a long time with strong rsa keys, but you could switch to ecc)… At this point you’d have to microwave your screen, your graphic card… and probably also… your whole computer. You shouldn’t also forget to also destroy the device flashing the Qr code then…

                    1. 6

                      Many enterprisey printers explicitly have a long memory of what they printed.

                      1. 1

                        I like the idea of drawing it by hand, but I bet it would go way faster with a typewriter that could print out some nice blocky squares… Hmmmm….

                    1. 6

                      The sloppiness of this release is concerning.

                      1. the link to the downloads goes to a page with an invalid cert, the cert is only valid for milliways.cryptomilk.org.
                      2. the report isn’t spell-checked: the attacker could successfully authentciate without any credentials

                      #2 is pretty minor, but attention to detail should be a strong feature for maintainers of software like this.

                      1. 1

                        I don’t see the ① issue? The download page is on www.libssh.org just like the news article, and that domain has a proper TLS cert. The only link to cryptomilk.org I can see is as an example keyserver for the GPG key whose fingerprint is given on the download page. And going there, that TLS cert looks right too. (Maybe it was fixed in the meantime?) In any case cryptomilk.org appears completely unrelated to www.libssh.org.

                        Am I missing something?

                        1. 1

                          Evidently the issue was fixed :)

                      1. 3

                        I know it wouldn’t help with caching but would it be possible to produce very small docker images if a Nix tool would only ship the right .so files and their dependencies? (like libpthread.so and a couple of others instead of the whole glibc folder).

                        1. 4

                          Nix doesn’t have knowledge down to that layer, but it could be possible. Another interesting thing along these lines is Nixpkgs is gaining the option to compile fully static binaries with musl for some packages.

                        1. 3

                          Is Nix actually doing bit for bit binary reproducible builds?

                          Edit: like reproducible-builds.org

                          1. 10

                            In many cases, yes we do produce bit-for-bit reproducible builds. A substantial amount of Nixpkgs produces bit-for-bit reproducible builds. Nix has built-in tools to help verify that, too, like --check and the repeat option: https://nixos.org/nix/manual/#conf-repeat

                            1. 2

                              Nix “derivations” (roughly, build products) are categorised as “fixed output” or not. All Nix derivations are identified using a hash, based on their inputs, but fixed output derivations also have another hash hard-coded in their metadata. After the build has finished, the output is checked against this hash and Nix will abort if they don’t match. This is mostly used for downloading/checking out source code, to prevent problems caused by URLs serving up different files. Fixed output derivations aren’t guaranteed to be reproducible (e.g. if the URL’s content has changed), but it does guarantee that if it succeeds then the output will be identical (modulo hash collisions).

                              Derivations which aren’t fixed-output don’t have their output checked in this way, so reproducibility mostly comes down to trusting the build scripts. As @grahamc says, Nix has facilities to compare the output of two runs of the same build and see if they’re the same.

                              On a related note there is also a feature for “intentional” builds: these take normal build outputs, identified by the hashes of their inputs, and allow them to be referred to by the hash of their outputs.

                            1. 1

                              As a genuine question from someone who hasn’t used procedural programming productively before, what would be the benefits of a procedural language to justify its choice?

                              1. 3

                                I would say less conceptual/cognitive overhead, but I don’t know if that’s something that can be said of this language as a whole, as I have no experience with it.

                                By that I mean something like: I have a rough idea of what code I want from the compiler, how much mental gymnastics is required to arrive at the source-level code that I need to write?

                                I would imagine that’s an important consideration in a language designed for game development.

                                1. 4

                                  Yeah, it makes perfect sense.

                                  To dumb down Kit’s value prop, it’s a “Better C, for people who need C (characteristics)”.

                                2. 2

                                  On top of alva’s comment, they compile fast and are easy to optimize, too.

                                  1. 1

                                    I looked this up for some other article on lobste.rs. I found wikipedia to have a nice summary


                                    Imperative programming

                                    Procedural programming languages are also imperative languages, because they make explicit references to the state of the execution environment. This could be anything from variables (which may correspond to processor registers) to something like the position of the “turtle” in the Logo programming language.

                                    Often, the terms “procedural programming” and “imperative programming” are used synonymously. However, procedural programming relies heavily on blocks and scope, whereas imperative programming as a whole may or may not have such features. As such, procedural languages generally use reserved words that act on blocks, such as if, while, and for, to implement control flow, whereas non-structured imperative languages use goto statements and branch tables for the same purpose.

                                    My understanding is that if you use say C you are basically using procedural language paradigms.

                                    1. 2

                                      Interesting. So basically what was registering in my mind as imperative programming is actually procedural.

                                      Good to know. Thanks for looking it up!

                                      1. 2

                                        I take “imperative” to mean based on instructions/statements, e.g. “do this, then do that, …”. An “instruction” is something which changes the state of the world, i.e. there is a concept of “before” and “after”. Lots of paradigms can sit under this umbrella, e.g. machine code (which are lists of machine instructions), procedural programming like C (where a “procedure”/subroutine is a high-level instruction, made from other instructions), OOP (where method calls/message sends are the instructions).

                                        Examples of non-imperative languages include functional programming (where programs consist of definitions, which (unlike assignments) don’t impose a notion of “before” and “after”) and logic programming (similar to functional programming, but definitions are more flexible and can rely on non-deterministic search to satisfy, rather than explicit substitution)

                                        1. 1

                                          If functional programs don’t have a noton of before and after, how do you code an algorithm? Explain newton’s method as a definition.

                                            1. 1

                                              both recursion and iteration say “do this, then do that, then do … “. And “let” appears to be assignment or naming so that AFTER the let operation a symbol has a meaning it did not have before.

                                              open some namespaces
                                              open System
                                              open Drawing    
                                              open Windows.Forms
                                              open Math
                                              open FlyingFrog

                                              changes program state so that certain operations become visible AFTER those lines are executed, etc.

                                              1. 3

                                                It is common for computation to not actually take place until the result is immediately needed. Your code may describe a complicated series of maps and filters and manipulations and only ever execute enough to get one result. Your code looks like it describes a strict order the code executes in, but the execution of it may take a drastically different path.

                                                A pure functional programming language wouldn’t be changing program state, but passing new state along probably recursively.

                                                1. 1

                                                  but you don’t really have a contrast with “imperative” languages - you still specify an algorithm. In fact, algorithms are all over traditional pure mathematics too. Generally the “state” being changed is on a piece of paper or in the head of the reader, but …

                                                2. 1

                                                  so that AFTER the let operation

                                                  If we assume that let is an operation, then there is certainly a before and an after.

                                                  That’s not the only way to think about let though. We might, for example, treat it as form of linguistic shorthand; for example treating:

                                                  let x = somethingVeryLongWindedInvolving y in x * x

                                                  as a shorthand for:

                                                  (somethingVeryLongWindedInvolving y) * (somethingVeryLongWindedInvolving y)

                                                  There is no inherent notion of before/after in such an interpretation. Even if our language implements let by literally expanding/elaborating the first form into the second, that can take place at compile time, alongside a whole host of other transformations/optimisations; hence even if we treat the expansion as a change of state, it wouldn’t actually occur at run time, and thus does not affect the execution of any algorithm by our program.

                                                  Note that we might, naively, think that the parentheses are imposing a notion of time: that the above tells us to calculate somethingVeryLongWindedInvolving y first, and then do the multiplication on the results. Call-by-name evaluation shows that this doesn’t have to be the case! It’s perfectly alright to do the multiplication first, and only evaluate the arguments if/when they’re needed; this is actually preferable in some cases (like the K combinator).

                                              2. 2

                                                If functional programs don’t have a noton of before and after, how do you code an algorithm?

                                                Roughly speaking, we define each “step” of an algorithm as a function, and the algorithm itself is defined as the result of (some appropriate combination of) those functions.

                                                As a really simple example, let’s say our algorithm is to reverse a singly-linked-list, represented as nested pairs [x0, [x1, [x2, ...]]] with an empty list [] representing the “end”. Our algorithm will start by creating a new empty list, then unwrap the outer pair of the input list, wrap that element on to its new list, and repeat until the input list is empty. Here’s an implementation in Javascript, where reverseAlgo is the algorithm I just described, and reverse just passes it the new empty list:

                                                var reverse = (function() {
                                                  function reverseAlgo(result, input) {
                                                    return (input === [])? result : reverseAlgo([input[0], result], input[1]);
                                                  return function(input) { return reverseAlgo([], input); };

                                                Whilst Javascript is an imperative language, the above is actually pure functional programming (I could have written the same thing in e.g. Haskell, but JS tends to be more familiar). In particular, we’re only ever defining things, in terms of other things. We never update/replace/overwrite/store/retrieve/etc. This style is known as single assignment.

                                                For your Newton-Raphson example, I decided to do it in Haskell. Since it uses Float for lots of different things (inputs, outputs, epsilon, etc.) I also defined a bunch of datatypes to avoid getting them mixed up:

                                                module Newton where
                                                newtype Function   = F (Float -> Float)
                                                newtype Derivative = D (Float -> Float)
                                                newtype Epsilon    = E Float
                                                newtype Initial    = I Float
                                                newtype Root       = R (Float, Function, Epsilon)
                                                newtonRaphson :: Function -> Derivative -> Epsilon -> Initial -> Root
                                                newtonRaphson (F f) (D f') (E e) (I x) = if abs y < e
                                                                                            then R (x, F f, E e)
                                                                                            else recurse (I x')
                                                  where y  = f x
                                                        x' = x - (y / f' x)
                                                        recurse = newtonRaphson (F f) (D f') (E e)

                                                Again, this is just defining things in terms of other things. OK, that’s the definition. So how do we explain it as a definition? Here’s my attempt:

                                                Newton’s method of a function f + guess g + epsilon e is defined as the “refinement” r of g, such that f(r) < e. The “refinement” of some number x depends on whether x satisfies our epsilon inequality: if so, its refinement is just x itself; otherwise it’s the refinement of x - (f(x) / f'(x)).

                                                This definition is “timeless”, since it doesn’t talk about doing one thing followed by another. There are causal relationships between the parts (e.g. we don’t know which way to “refine” a number until we’ve checked the inequality), but those are data dependencies; we don’t need to invoke any notion of time in our semantics or understanding.

                                                1. 2

                                                  Our algorithm will start by creating a new empty list, then unwrap the outer pair of the input list, wrap that element on to its new list, and repeat until the input list is empty.

                                                  Algorithms are essentially stateful. A strongly declarative programming language like Prolog can avoid or minimize explicit invocation of algorithms because it is based on a kind of universal algorithm that is applied to solve the constraints that are specified in a program. A “functional” language relies on a smaller set of control mechanisms to reduce, in theory, the complexity of algorithm specification, but “recursion” specifies what to do when just as much as a “goto” does. Single assigment may have nice properties, but it’s still assignment.

                                                  To me, you are making a strenuous effort to obfuscate the obvious.

                                                  1. 3

                                                    Algorithms are essentially stateful.

                                                    I generally agree. However, I would say programming languages don’t have to be.

                                                    When we implement a stateful algorithm in a stateless programming language, we need to represent that state somehow, and we get to choose how we want to do that. We could use successive “versions” of a datastructure (like accumulating parameter in my ‘reverse’ example), or we could use a call stack (very common if we’re not making tail calls), or we could even represent successive states as elements of a list (lazy lists in Haskell are good for this).

                                                    A strongly declarative programming language like Prolog can avoid or minimize explicit invocation of algorithms because it is based on a kind of universal algorithm that is applied to solve the constraints that are specified in a program.

                                                    I don’t follow. I think it’s perfectly reasonable to say that Prolog code encodes algorithms. How does Prolog’s use of a “universal algorithm” (depth-first search) imply that Prolog code isn’t algorithmic? Every programming language is based on “a kind of universal algorithm”: Python uses a bytecode interpreter, Haskell uses beta-reduction, even machine code uses the stepping of the CPU. Heck, that’s the whole point of a Universal Turing Machine!

                                                    “recursion” specifies what to do when just as much as a “goto” does.

                                                    I agree that recursion can be seen as specifying what to do when; this is a different perspective of the same thing. It’s essentially the contrast between operational semantics and denotational semantics.

                                                    I would also say that “goto” can be seen as a purely definitional construct. However, I don’t think it’s particularly useful to think of “goto” in this way, since it generally makes our reasoning harder.

                                                    To me, you are making a strenuous effort to obfuscate the obvious.

                                                    There isn’t “one true way” to view these things. I don’t find it “strenuous” to frame things in this ‘timeless’ way; indeed I personally find it easier to think in this way when I’m programming, since I don’t have to think about ‘time’ at all, just relationships between data.

                                                    Different people think differently about these things, and it’s absolutely fine (and encouraged!) to come at things from different (even multiple) perspectives. That’s often the best way to increase understanding, by find connections between seemingly unrelated things.

                                                    Single assigment may have nice properties, but it’s still assignment.

                                                    In name only; its semantics, linguistic role, formal properties, etc. are very different from those of memory-cell-replacement. Hence why I use the term “definition” instead.

                                                    The key property of single assignment is that it’s unobservable by the program. “After” the assignment, everything that looks will always see the same value; but crucially, “before” the assignment nothing is able to look (since looking creates a data dependency, which will cause that code to be run “after”).

                                                    Hence the behaviour of a program that uses single assignment is independent of when that assignment takes place. There’s no particular reason to assume that it will take place at one time or another. We might kid ourselves, for the sake of convenience, that such programs have a state that changes over time, maybe going to far as to pretend that these hypothetical state changes depend in some way on the way our definitions are arrangement in a text file. Yet this is just a (sometimes useful) metaphor, which may be utterly disconnected from what’s actually going on when the program (or, perhaps, a logically-equivalent one, spat out of several stages of compilation and optimisation!).

                                                    Note that the same is true of the ‘opposite’ behaviour: garbage collection. A program’s behaviour can’t depend on whether or not something has been garbage collected, since any reference held by such code will prevent it from being collected! Garbage collection is an implementation detail that’s up to the interpreter/runtime-system; we can count on it happening “eventually”, and in some languages we may even request it, but adding it to our semantic model (e.g. as specific state transitions) is usually an overcomplication that hinders our understanding.

                                                    1. 1

                                                      A lot of what you see as distinctive in functional languages is common to many non-functional languages. And look up Prolog - it is a very interesting alternative model.

                                                      1. 1

                                                        A lot of what you see as distinctive in functional languages is common to many non-functional languages.

                                                        You’re assuming “what I see”, and you’re assumption is wrong. I don’t know where you got this idea from, but it’s not from me.

                                                        I actually think of “functional programming” as a collection of styles/practices which have certain themes in common (e.g. immutability). I think of “functional programming languages” as simply those which make programming in a functional style easier (e.g. eliminating tail calls, having first-class functions, etc.) and “non-functional programming languages” as those which make those styles harder. Most functional programming practices are possible in most languages.

                                                        In other words, I agree that “A lot of [features of] functional languages is common to many non-functional languages”, but I have no idea why you would claim I didn’t.

                                                        Note that in this thread I’ve not tried to claim that, e.g. “functional programming languages are better”, or anything of that nature. I was simply stating the criteria I use for whether to call a style/language “imperative” or not; namely, if its semantics are most usefully understood as executing instructions to change the state of the (internal or external) world.

                                                        And look up Prolog - it is a very interesting alternative model.

                                                        I’m well aware of Prolog. The research group I was in for my PhD did some fascinating work on formalising and improving logic programming in co-inductive settings; although I wasn’t directly involved in that. For what it’s worth I’m currently writing a project in Mercury (a descendent of Prolog, with static types among other things).

                                          1. 1

                                            So procedural languages are similar to imperative languages, but with somewhat more abstraction?

                                        1. 5

                                          What’s the point of using DocBook over HTML5? Every one of the elements described maps 1:1 to an HTML5 element. Is it because there’s a larger set of tools to take DocBook and typeset it for printing? Or is the verbosity of DocBook a usability advantage (<para> V.S. <p>)?

                                          1. 3

                                            Great question!

                                            DocBook has lots of tools for rendering, to much more than just HTML: Literal books, PDFs, manpages, knowledgebases, even special formats for some editors to find and interpret and provide contextual help on a project.

                                            DocBook has special tags to help represent EBNF and functions and types and GUIs and error messages and function arguments and command line program options and variable names and and and and.

                                            Yes, every element described maps 1:1 but there are hundreds more which are undescribed by this post and are useful for large documentation projects.

                                            Edited to say: much of this is not strictly necessary for getting started and writing some docs, which is the goal of this document. It is so easy to look at the massive amount of tags and try and pick the most perfect semantics for your writing when the truth is having any docs being contributed is much more important. Leave the precise and fiddly semantics to the maintainers and PR reviewers. Let’s just write some docs.

                                            1. 2

                                              I’ve been considering building a system to auto-generate documentation from the source code and comments of different languages into a common format with no styling information. Would DocBook be a good format-of-record for my project?

                                              I’d like to use the preferred tool for each language to extract comments-based docs, and then a single new tool to combine source-derived documentation with human-authored guides into a final presentation format:

                                              • Ruby -> YARD -> DocBook
                                              • Java -> Javadoc -> DocBook
                                              • Lang -> Native tool for Lang -> DocBook
                                              • Markdown -> DocBook

                                              Then at the end, I can take all the DocBook and unify the presentation style:

                                              • DocBook -> HTML
                                              1. 1

                                                You could try integrating pandoc, it has a Lua or Haskell API, and an internal intermediate representation: https://pandoc.org/index.html

                                              2. 1

                                                Follow up questions: what toolchain do you use?

                                                And are there styles for rendering docbook that feel satisfactory for people used to latex typesetting?

                                            1. 7

                                              Bad idea, it should error or give NaN.

                                              1/0 = 0 is mathematically sound

                                              It’s not mathematically sound.

                                              a/b = c should be equivalent to a = c*b

                                              this fails with 1/0 = 0 because 1 is not equal to 0*0.

                                              Edit: I was wrong, it is mathematically sound. You can define x/0 = f(x) any function of x at all. All the field axioms still hold because they all have preconditions that ensure you never look at the result of division by zero.

                                              There is a subtlety because some people say (X) and others say (Y)

                                              • (X) a/b = c should be equivalent to a = c*b when the LHS is well defined

                                              • (Y) a/b = c should be equivalent to a = c*b when b is nonzero

                                              If you have (X) definition in mind it becomes unsound, if you are more formal and use definition (Y) then it stays sound.

                                              It seems like a very bad idea to make division well defined but the expected algebra rules not apply to it. This is the whole reason we leave it undefined or make it an error. There isn’t any value you can give it that makes algebra work with it.

                                              It will not help programmers to have their programs continue on unaware of a mistake, working on with corrupt values.

                                              1. 14

                                                I really appreciate your follow-up about you being wrong. It is rare to see, and I commend you for it. Thank you.

                                                1. 8

                                                  This is explicitly addressed in the post. Do you have any objections to the definition given in the post?

                                                  1. 13

                                                    I cover that exact objection in the post.

                                                    1. 4

                                                      It will not help programmers to have their programs continue on unaware of a mistake, working on with corrupt values

                                                      That was my initial reaction too. But I don’t think Pony’s intended use case is numerical analysis; it’s for highly parallel low-latency systems, where there are other (bigger?) concerns to address. They wanted to have no runtime exceptions, so this is part of that design tradeoff. Anyway, nothing prevents the programmer from checking for zero denominators and handling them as needed. If you squint a little, it’s perhaps not that different from the various conventions on truthy/falsey values that exist in most languages, and we’ve managed to accommodate to those.

                                                      1. 4

                                                        Those truthy/falsey values are an often source of errors.

                                                        I may be biased in my dislike of this “feature”, because I cannot recall when 1/0 = 0 would be useful in my work, but have no difficulty whatsoever thinking of cases where truthy/falsey caused problems.

                                                      2. 4

                                                        1/0 is integer math. NaN is available for floating point math not integer math.

                                                        1. 2

                                                          It will not help programmers to have their programs continue on unaware of a mistake, working on with corrupt values.

                                                          I wonder if someone making a linear math library for Pony already faced this. There are many operations that might divide by zero, and you will want to let the user know if they divided by zero.

                                                          1. 7

                                                            It’s easy for a Pony user to create their own integer division operation that will be partial. Additionally, a “partial division for integers” operator has been been in the works for a while and will land soon. Its part of operators that will also error if you have integer overflow or underflow. Those will be +?, /?, *?, -?.


                                                        1. 4

                                                          I’m interested in the pretty impressive performance delta – I wouldn’tve thought that Zen could outperform Broadwell quite so handily!

                                                          1. 2

                                                            Me too! I’ll be completely honest: I have no idea what factors contributed here. Maybe things like no NUMA? a bit more cache? Something with Spectre / Meltdown? No idea – not my forte – but I am sure delighted by it.

                                                            1. 8

                                                              EPYC is way more NUMA than Intel equivalents. EPYC has four dies on one package, and each die is a NUMA domain.

                                                              But Meltdown mitigations are indeed usually only turned on for Intel! :)

                                                              1. 1

                                                                Disk possibly?

                                                            1. 15

                                                              Rust meanwhile notes that you can’t safely write a performant data structure in Rust, so they urge you not to do that.

                                                              The interesting thing to me is the linked FAQ (https://www.rust-lang.org/en-US/faq.html#can-i-implement-linked-lists-in-rust) literally doesn’t say that.

                                                              It says:

                                                              1. Efficient implementations of many data structures are provided by the standard library.
                                                              2. Most data structures can be done in safe Rust, but for comparable performance, some would be better implemented using unsafe Rust. Not that it is impossible.
                                                              3. Goes on to provide a specific example of how to do a doubly linked list in safe Rust, and describes how to do it also with unsafe Rust for better performance.

                                                              I wonder if this was an oversight or misunderstanding?

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                                                                As a follow-up, in the conclusion you say:

                                                                I think that in practice they may not be making real life shipped code a lot more secure - also because not that much actual Rust code is shipping.

                                                                While just one of the undoubtedly many examples which could be brought up, I hadn’t realized the Quantum CSS engine from Firefox was so short! More seriously, the achievements in Firefox are remarkable and inspiring, and is a large amount of code shipping to real users, and used every day.

                                                                One thing I like very much about the borrow checker is it took memory access problems and turned it in to a generic resource safety problem. Using the simple primitives available I’m able to easily encode usage requirements, limitations, and state changes through borrows and Drops and have them checked at compile time. This is really powerful, and I very much appreciate it.

                                                                For whatever it is worth, I’m a rubbish C dev – not to be trusted to write a single line – who has found Rust to be an comfortable and pleasant experience in only a few weeks of free-time practice.

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                                                                  Hi - I worded this incorrectly. What I meant to say was that the FAQ says performance will disappoint unless you go into unsafe mode. “For example, a doubly-linked list requires that there be two mutable references to each node, but this violates Rust’s mutable reference aliasing rules. You can solve this using Weak, but the performance will be poorer than you likely want. With unsafe code you can bypass the mutable reference aliasing rule restriction, but must manually verify that your code introduces no memory safety violations.”. I’ve updated the wording a bit. Apologies for the confusion.

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                                                                    It is improved, but they don’t urge you to not do it. However, still, unsafe Rust is still safer than C.

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                                                                      Oh boy, what a quote.

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                                                                        It definitely is in context of bigger picture. The default in C for doing Rust’s level of safety is separation logic with tools like VCC. Hard to learn, slow to develop (2loc/day at one point), and solvers likely slower than compiler checks. Rust brought that level of safety to most apps using a simplified model and checker. Both the checker and resulting code usually perform well. The quote indicates it can’t handle some optimized, low-level, data structures. Those atypical cases will need verification with external tool or method.

                                                                        In light of that, Rust gets safer code faster than C in most verification cases but maybe equivalent labor in some. Rust still seems objectively better than C on being safe, efficient, and productively so.

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                                                                          there are languages in which linked lists are primitives or maybe even invisible. But if you are going to specify a language for writing programs that include linked lists, you should not have to use pragmas. This is a characteristic computer science trope: “we have a rigorous specification of this which cannot ever be violated unless you push the magic button”. It’s a way of acting as if you have solved a problem that you have simply hidden.

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                                                                    Very cool program! So exciting to see .nix files already there!

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                                                                      Glad you like it :) All the .nix credit goes to nmattia, but let me know in the issue tracker if you run into trouble. Afaik it only works with the unstable channel (and we didn’t pin the nixpkgs version yet).

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                                                                      Nice upgrades to 2TB SSDs.

                                                                      Personally find it funny how OpenGrok is so bloated that it still has to run on the spindles, hugging along next to the backups — even a 512GB SSD is no fit when you’re dealing with Enterprise-level software written in Java. :-)

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                                                                        I wonder if they’ve examined Hound – https://github.com/etsy/hound – I’ve found it to be much more performant when compared to OpenGrok, while still providing excellent results.

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                                                                        Is the only difference between Guix and Nix the language? I know Nix is more mature and has a bigger community with more packages, but I don’t see any user-facing changes between the two.

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                                                                          I guess there are many differences? One important one is the license. The FSF prefers Guix and GuixSD over Nix and NixOS.

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                                                                            that’s…not really…a difference in the technology

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                                                                              Oh, you wanted only technological differences? Sorry about that. :)

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                                                                            Guix is or was based on the Nix daemon and essentially just a fork, substituting the Nix language for scheme, plus the requirements for packaging. This was several years ago now, it may have diverged further.

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                                                                            I wonder if the Firefox build team has considered exploring Nix for allowing the builders to be internet-free, but without bundling dependencies in the repo.

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                                                                              Does Nix work on Windows? Firefox build team must produce Windows binary, in fact, it is the most important build in terms of users.

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                                                                                My understanding is that it works on the WSL, but that’s not real Windows.

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                                                                              Way to go Domen! I completely agree, the Nix ecosystem needs tools like Cachix to support Nix in production and at small companies. I’m delighted to see this released, and look forward to giving it a try this weekend!

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                                                                                May I recommend putting in paragraph zero, “Use shellcheck, dummy!”?

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                                                                                  It’s in the readme. The linked document is meant as an addendum. I’ll think about it.

                                                                                  Update: Added a preface.

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                                                                                  That’s interesting that the company behind it is CZ.NIC the owner/operator of the .cz domain name!

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                                                                                    And also the authors of Knot, the DNS services behind

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