8 ms·

> And sure, `snowflake >> 22` would be shorter, clearer, and far more efficient, but it wouldn't let you show off all the cool language features you have at you

> And sure, `snowflake >> 22` would be shorter, clearer, and far more efficient, but it wouldn't let you show off all the cool language features you have at your disposal, and isn't that what's really important? I don't think the over-complicated code was motivated by a desire to show off — it was written by someone who doesn't understand how bit shifts work, which is still potentially troubling but very different

kasey_junk 5y ago
Or that simply has never had reason to use them so didn’t think to look for them.
- PaulHoule 5y ago
  I never found C style operators for bit twiddling to be intuitive (compared to assembly) even if you use the left angle brace to shift left.
  - the_only_law 5y ago
    While this example is a pretty simple and I agree that a bit shift is a fine solution, I’ve recently been doing work on some bit-oriented HDLC-like protocols I’m convinced Erlang is the only language that can manipulate binary data very well at the bit level.
    - codesections 5y ago
      Out of curiosity, what makes the Erlang syntax so good?
      - the_only_law 5y ago
        It's super easy to construct binaries and bitstrings even when you need to work with award sizes or set bits at weird positions and IMO looks a lot cleaner than a lot of shifting and boolean operators. For example constructing a 8-bit LAPB Information transfer control field might look like: build_info_control(SendSeq, RecvSeq, Poll) -> <<0:1, SendSeq/bitstring, Poll/bitstring, RecvSeq/bitstring>>. Where the `SendSeq` and `RecvSeq` are 3-bit sequence numbers... say one of them is `<<2:3>>` (0b010) and Poll is a single bit (you can see the format here: https://imgur.com/a/9bVBM0W https://imgur.com/a/9bVBM0W). This field would then be stuck into a binary representing the entire frame. This could probably be made a littler simpler, though, as I'm still rather new to Erlang. Note you also do get bit shift operators for cases when they’re an appropriate solution (`bsl` and `bsr`)
        voidnullnil 5y ago
        (As someone strongly against adding new features to languages,) I've never understood where there would be any need for anything more complicated than list concatenation when assembling bits. In some language with list notation, (++ being concatenation of two lists) you could do something like this: [0] ++ sendSeq ++ recvSeq ++ [poll] say sendSeq was one bit but we still wanted it to take 3 bits: [0] ++ pad 3 sendSeq ++ poll ++ recvSeq given some "pad" function defined in a library The only reason it's "hard" in C is because the operations are induced from what the machine can do efficiently and without "a sufficiently smart compiler".
        macintux 5y ago
        The bit syntax in Erlang is for deconstruction and assignment (pattern matching), not just assembling. The entire language is built around pattern matching to the point where it simply wouldn't exist otherwise, and I assume binary protocol handling was a core requirement when the language was designed since it was created for telecom switches.
        Jtsummers 5y ago
        https://erlang.org/doc/programming_examples/bit_syntax.html https://erlang.org/doc/programming_examples/bit_syntax.html > say sendSeq was one bit but we still wanted it to take 3 bits: > [0] ++ pad 3 sendSeq ++ poll ++ recvSeq In Erlang you could do this to get something padded (or truncated) to the correct size: << 2:3 >> ;; corresponds to the 3 bits <<010>> So you can do something like this to ensure the precise bit size of each field: << 0:1, SendSeq:3, Poll:3, RecvSeq:3>>
        voidnullnil 5y ago
        Yaeh, my point was that it is trivial to define a pad function and call it instead of needing some syntax like Erlang. But now I see there is deconstruction too, which is more arguably useful to take the time to add syntax for.
        spc476 5y ago
        C has the concept of bit fields, and this could be specified as: struct build_info_control { unsigned char : 1; unsigned char SendSeq : 3; unsigned char Poll : 1; unsigned char RecvSeq : 3; }; struct build_info_control control; control.SendSeq = sendSeq; control.Poll = true; control.RecvSeq = recvSeq; The downside of bit fields is that they are implementation specific---you'll have to check the compiler documentation to see if the bits are specified "most significant bit to least significant bit" or "least significant bit to most significant bit" (if that is indeed, important to the problem).
    - dnautics 5y ago
      elixir too, since the underlying technology is the same (arguably it's even easier to read in elixir than erlang). This was super helpful when I was writing a dhcp server.
    - kiadimoondi 5y ago
      Agreed. I was writing a port of the redis protocol to erlang for a personal project that's a server using said protocol as an interface for distributed MPSC "locking", and it was incredibly simple to implement because of erlang's binary strings and pattern matching. Same with base64/hex/etc. manipulations of strings into binary data. I've read a fair bit about how erlang is great for protocols, but hadn't experienced it myself (professionally or personally) until I decided to implement this project.
  - mdip 5y ago
    I learned these operators in a college course I took while in High School[0]. I remember I had to make flash cards with examples and memorize throughout the semester. I kept mixing up & and | in comparison/setting. It's still rare that I use anything outside of those two operators in work code, and when I do it tends to get commented as a premature optimization during code reviews. [0] That's not a humble-brag, context provided b/c it's a time, due to 7 hours a day spent taking tests/memorizing and spent also learning algebra through calculus, I was at my absolute peek for learning this sort of thing.
  - marcosdumay 5y ago
    The existence of a single pair of operators, instead of one for signed and another for unsigned shifts (with good names) make the operators impossible to remember to me. Ok, the article just made me remember they are not signed. But it's certain that the next time I need them, I won't remember it again.
  - CRConrad 5y ago
    > I never found C style operators for bit twiddling to be intuitive (compared to assembly) even if you use the left angle brace to shift left. What I don't get: Are those operators present in C++ too -- wouldn't they clash with the "streaming" thingamajigs, isn't that what "<<" means nowadays?
- cm2187 5y ago
  Or perhaps for a rarely called function, and which was quicker to write via an inefficient but familiar method rather than spend any time figuring out how to do it in an optimal and correct way.
growt 5y ago
My guess is this was written as a joke. It's rust, so the person writing this has to have some programming knowledge.
- codesections 5y ago
  "some programming knowledge" ≠ "knowledge of bit operators" Imo, Rust makes a very good second language for someone who first learned Javascript or Ruby — and someone who used those languages primarily for web dev may never have needed to learn about bit shifts
  - afandian 5y ago
    I find it hard to believe that someone simultaneously doesn't know the first thing about bit operations, but has come to the conclusion that they need to find the first 42 bits. Also, JavaScript's handling of numbers is so weird that it's one of those things that comes up just by virtue of its weirdness. For that reason I'd expect a JS programmer at least have come across but operations. (edit - I take the original post as a joke too, and that the humour is derived from the juxtaposition)
    - mdip 5y ago
      Both very good points -- I hadn't originally assumed it was a joke, mostly because I don't write `rust` code and I don't know how unlikely it would be to come to that solution. I know I've seen examples at least as odd as this in the past in languages I'm familiar with -- where, say, the developer was really good with LINQ or something and made five calls instead of just accessing an array by index -- that were meant "intentionally", but were bizarre to someone not sitting in their brain at that moment. I hadn't, however, thought about either of the points you mentioned. You're quite the detective. :)
    - voidnullnil 5y ago
      Most JS programmers are utterly unaware of how their "numbers" work.
- 5y ago
mdip 5y ago
> which is still potentially troubling but very different I'm having a really difficult time remembering the last time I had to even use a bit operator at work[0]. For a lot of developers, the need to keep that operator in their head is going to rank way lower than, say, how to properly configure CORS in `ngninx`. You always have to judge a developer's gaps/knowledge given their context. We're dealing in technologies that have sub-sub-sub-sub-disciplines that a person may have expertise in which result in them missing huge portions of the languages' features. I've learned that this hyper-specialized developer can be as effective as anyone -- the ability to rapidly acquire, integrate and use new knowledge with whatever tooling is required is far more important to me than whether or not a developer has large gaps in the tools we use[1]. I'm nit-picking a little, but it's a habit of mine to turn around discussions at my office that go something like "How can any web developer not know (x)?"[2] Ask a developer on a conference call if they're familiar with some obscure technology, and you'll hear ranges of qualified "Yes" responses and a whole bunch of clacking while each Google's various bits of information. How much easier is it if everyone just says "No, I don't" and asks the person who brought it up to explain. It's really hard to get developers past "Imposter Syndrom" and open to admitting their gaps so they can be accounted for in planning. Even where I'm at, now, I see it from time to time and this is at a shop with excellent culture and a focus on projects/products that are new inventions/creations. And, unfortunately, it causes me to judge that individual unfairly, myself -- I've been writing code since I was 13 years old. I have written a lot of code. My goal is that the best code I wrote 6 months ago should at least slightly embarrass me, today.[3] And I guarantee, over the years, I've written code that is worthy of posting on a site like this. I can't imagine what kind of insanity my first "useful" rust program will end up looking like, but given the memory-safety rules imposed, I'm expecting to have to integrate a new mental model that will result in some comical implementations. For me -- this work has a way of either humbling you or down-right beating you up with how often you're reminded about what you don't know. I think it gets worse as you learn more almost feeding the whole "ageism" in the industry -- middle-aged developers are far more honest about what they don't know and some are just beaten to death by the treadmill. I have watched, over the years, as developer after developer has left for "management" or leaving a shop like the one I'm at for a global multi-national to work on the most boring internal enterprise-y waste -- consistent/easy, but pointless. For the few that I was close enough to that I got more than just "PR answers", the crux of it was burn out from never feeling like you're actually "knowing" less about what you're working on[4] [0] Outside of `enum`s in my language of choice, which perform best when flags are checked/appended using operators. But even that is an unnecessary optimization nearly always, there's a ".HasFlag()" method that I simply forget about because it was taught to me in my teens, it's implemented consistently in a lot of languages and it's muscle memory at times. [1] I've recommended the hire of individuals who, outside of "they have been writing C# code for a decade", they hadn't touched the part of the framework the job was for -- i.e. they were Desktop devs applying to Web, Web applying to mobile, and many candidates lack even basic Docker/shell knowledge, etc. All ended up picking up what they were missing on-the-job just like the rest of us. [2] Because, unlike every other field, when "(x)" became "old", it had been on its 5th version, 4th major API change and was born about three and a half minutes ago. [3] Sometimes I'm unfair -- the reason I'm embarrassed is because I didn't use a very obvious feature, but at the time I'm looking at the code I'm also forgetting that said feature didn't exist back then. But often it's just because I've continued to read/study/do. [4] These were not developers who were suffering from mental decline with age and were among the better I've worked with. I really think it's a case of "learning about something new" simultaneously adding to "discovering that your skillset does not include this massive body of knowledge around your small usage of 'something new'". You learn way more about how much you don't know than you add to your total knowledge making you feel 'net dumber'.
voidnullnil 5y ago
The author could have been unaware that it's possible to program computers without knowledge of binary arithmetic and bit level operations.

kasey_junk 5y ago

Or that simply has never had reason to use them so didn’t think to look for them.

PaulHoule 5y ago
I never found C style operators for bit twiddling to be intuitive (compared to assembly) even if you use the left angle brace to shift left.
- the_only_law 5y ago
  While this example is a pretty simple and I agree that a bit shift is a fine solution, I’ve recently been doing work on some bit-oriented HDLC-like protocols I’m convinced Erlang is the only language that can manipulate binary data very well at the bit level.
  - codesections 5y ago
    Out of curiosity, what makes the Erlang syntax so good?
    - the_only_law 5y ago
      It's super easy to construct binaries and bitstrings even when you need to work with award sizes or set bits at weird positions and IMO looks a lot cleaner than a lot of shifting and boolean operators. For example constructing a 8-bit LAPB Information transfer control field might look like: build_info_control(SendSeq, RecvSeq, Poll) -> <<0:1, SendSeq/bitstring, Poll/bitstring, RecvSeq/bitstring>>. Where the `SendSeq` and `RecvSeq` are 3-bit sequence numbers... say one of them is `<<2:3>>` (0b010) and Poll is a single bit (you can see the format here: https://imgur.com/a/9bVBM0W https://imgur.com/a/9bVBM0W). This field would then be stuck into a binary representing the entire frame. This could probably be made a littler simpler, though, as I'm still rather new to Erlang. Note you also do get bit shift operators for cases when they’re an appropriate solution (`bsl` and `bsr`)
      - voidnullnil 5y ago
        (As someone strongly against adding new features to languages,) I've never understood where there would be any need for anything more complicated than list concatenation when assembling bits. In some language with list notation, (++ being concatenation of two lists) you could do something like this: [0] ++ sendSeq ++ recvSeq ++ [poll] say sendSeq was one bit but we still wanted it to take 3 bits: [0] ++ pad 3 sendSeq ++ poll ++ recvSeq given some "pad" function defined in a library The only reason it's "hard" in C is because the operations are induced from what the machine can do efficiently and without "a sufficiently smart compiler".
        macintux 5y ago
        The bit syntax in Erlang is for deconstruction and assignment (pattern matching), not just assembling. The entire language is built around pattern matching to the point where it simply wouldn't exist otherwise, and I assume binary protocol handling was a core requirement when the language was designed since it was created for telecom switches.
        Jtsummers 5y ago
        https://erlang.org/doc/programming_examples/bit_syntax.html https://erlang.org/doc/programming_examples/bit_syntax.html > say sendSeq was one bit but we still wanted it to take 3 bits: > [0] ++ pad 3 sendSeq ++ poll ++ recvSeq In Erlang you could do this to get something padded (or truncated) to the correct size: << 2:3 >> ;; corresponds to the 3 bits <<010>> So you can do something like this to ensure the precise bit size of each field: << 0:1, SendSeq:3, Poll:3, RecvSeq:3>>
        voidnullnil 5y ago
        Yaeh, my point was that it is trivial to define a pad function and call it instead of needing some syntax like Erlang. But now I see there is deconstruction too, which is more arguably useful to take the time to add syntax for.
        spc476 5y ago
        C has the concept of bit fields, and this could be specified as: struct build_info_control { unsigned char : 1; unsigned char SendSeq : 3; unsigned char Poll : 1; unsigned char RecvSeq : 3; }; struct build_info_control control; control.SendSeq = sendSeq; control.Poll = true; control.RecvSeq = recvSeq; The downside of bit fields is that they are implementation specific---you'll have to check the compiler documentation to see if the bits are specified "most significant bit to least significant bit" or "least significant bit to most significant bit" (if that is indeed, important to the problem).
  - dnautics 5y ago
    elixir too, since the underlying technology is the same (arguably it's even easier to read in elixir than erlang). This was super helpful when I was writing a dhcp server.
  - kiadimoondi 5y ago
    Agreed. I was writing a port of the redis protocol to erlang for a personal project that's a server using said protocol as an interface for distributed MPSC "locking", and it was incredibly simple to implement because of erlang's binary strings and pattern matching. Same with base64/hex/etc. manipulations of strings into binary data. I've read a fair bit about how erlang is great for protocols, but hadn't experienced it myself (professionally or personally) until I decided to implement this project.
- mdip 5y ago
  I learned these operators in a college course I took while in High School[0]. I remember I had to make flash cards with examples and memorize throughout the semester. I kept mixing up & and | in comparison/setting. It's still rare that I use anything outside of those two operators in work code, and when I do it tends to get commented as a premature optimization during code reviews. [0] That's not a humble-brag, context provided b/c it's a time, due to 7 hours a day spent taking tests/memorizing and spent also learning algebra through calculus, I was at my absolute peek for learning this sort of thing.
- marcosdumay 5y ago
  The existence of a single pair of operators, instead of one for signed and another for unsigned shifts (with good names) make the operators impossible to remember to me. Ok, the article just made me remember they are not signed. But it's certain that the next time I need them, I won't remember it again.
- CRConrad 5y ago
  > I never found C style operators for bit twiddling to be intuitive (compared to assembly) even if you use the left angle brace to shift left. What I don't get: Are those operators present in C++ too -- wouldn't they clash with the "streaming" thingamajigs, isn't that what "<<" means nowadays?
cm2187 5y ago
Or perhaps for a rarely called function, and which was quicker to write via an inefficient but familiar method rather than spend any time figuring out how to do it in an optimal and correct way.

growt 5y ago

My guess is this was written as a joke. It's rust, so the person writing this has to have some programming knowledge.

codesections 5y ago
"some programming knowledge" ≠ "knowledge of bit operators" Imo, Rust makes a very good second language for someone who first learned Javascript or Ruby — and someone who used those languages primarily for web dev may never have needed to learn about bit shifts
- afandian 5y ago
  I find it hard to believe that someone simultaneously doesn't know the first thing about bit operations, but has come to the conclusion that they need to find the first 42 bits. Also, JavaScript's handling of numbers is so weird that it's one of those things that comes up just by virtue of its weirdness. For that reason I'd expect a JS programmer at least have come across but operations. (edit - I take the original post as a joke too, and that the humour is derived from the juxtaposition)
  - mdip 5y ago
    Both very good points -- I hadn't originally assumed it was a joke, mostly because I don't write `rust` code and I don't know how unlikely it would be to come to that solution. I know I've seen examples at least as odd as this in the past in languages I'm familiar with -- where, say, the developer was really good with LINQ or something and made five calls instead of just accessing an array by index -- that were meant "intentionally", but were bizarre to someone not sitting in their brain at that moment. I hadn't, however, thought about either of the points you mentioned. You're quite the detective. :)
  - voidnullnil 5y ago
    Most JS programmers are utterly unaware of how their "numbers" work.
5y ago

mdip 5y ago

> which is still potentially troubling but very different I'm having a really difficult time remembering the last time I had to even use a bit operator at work[0]. For a lot of developers, the need to keep that operator in their head is going to rank way lower than, say, how to properly configure CORS in `ngninx`. You always have to judge a developer's gaps/knowledge given their context. We're dealing in technologies that have sub-sub-sub-sub-disciplines that a person may have expertise in which result in them missing huge portions of the languages' features. I've learned that this hyper-specialized developer can be as effective as anyone -- the ability to rapidly acquire, integrate and use new knowledge with whatever tooling is required is far more important to me than whether or not a developer has large gaps in the tools we use[1]. I'm nit-picking a little, but it's a habit of mine to turn around discussions at my office that go something like "How can any web developer not know (x)?"[2] Ask a developer on a conference call if they're familiar with some obscure technology, and you'll hear ranges of qualified "Yes" responses and a whole bunch of clacking while each Google's various bits of information. How much easier is it if everyone just says "No, I don't" and asks the person who brought it up to explain. It's really hard to get developers past "Imposter Syndrom" and open to admitting their gaps so they can be accounted for in planning. Even where I'm at, now, I see it from time to time and this is at a shop with excellent culture and a focus on projects/products that are new inventions/creations. And, unfortunately, it causes me to judge that individual unfairly, myself -- I've been writing code since I was 13 years old. I have written a lot of code. My goal is that the best code I wrote 6 months ago should at least slightly embarrass me, today.[3] And I guarantee, over the years, I've written code that is worthy of posting on a site like this. I can't imagine what kind of insanity my first "useful" rust program will end up looking like, but given the memory-safety rules imposed, I'm expecting to have to integrate a new mental model that will result in some comical implementations. For me -- this work has a way of either humbling you or down-right beating you up with how often you're reminded about what you don't know. I think it gets worse as you learn more almost feeding the whole "ageism" in the industry -- middle-aged developers are far more honest about what they don't know and some are just beaten to death by the treadmill. I have watched, over the years, as developer after developer has left for "management" or leaving a shop like the one I'm at for a global multi-national to work on the most boring internal enterprise-y waste -- consistent/easy, but pointless. For the few that I was close enough to that I got more than just "PR answers", the crux of it was burn out from never feeling like you're actually "knowing" less about what you're working on[4] [0] Outside of `enum`s in my language of choice, which perform best when flags are checked/appended using operators. But even that is an unnecessary optimization nearly always, there's a ".HasFlag()" method that I simply forget about because it was taught to me in my teens, it's implemented consistently in a lot of languages and it's muscle memory at times. [1] I've recommended the hire of individuals who, outside of "they have been writing C# code for a decade", they hadn't touched the part of the framework the job was for -- i.e. they were Desktop devs applying to Web, Web applying to mobile, and many candidates lack even basic Docker/shell knowledge, etc. All ended up picking up what they were missing on-the-job just like the rest of us. [2] Because, unlike every other field, when "(x)" became "old", it had been on its 5th version, 4th major API change and was born about three and a half minutes ago. [3] Sometimes I'm unfair -- the reason I'm embarrassed is because I didn't use a very obvious feature, but at the time I'm looking at the code I'm also forgetting that said feature didn't exist back then. But often it's just because I've continued to read/study/do. [4] These were not developers who were suffering from mental decline with age and were among the better I've worked with. I really think it's a case of "learning about something new" simultaneously adding to "discovering that your skillset does not include this massive body of knowledge around your small usage of 'something new'". You learn way more about how much you don't know than you add to your total knowledge making you feel 'net dumber'.

voidnullnil 5y ago

The author could have been unaware that it's possible to program computers without knowledge of binary arithmetic and bit level operations.