10 ms·

Hard to tell if sarcastic, but anyway. I think the GOTOers just died out. Some day null, statements (rather than expressions) and side-effects will have alway

by mrkeen 17d ago

Hard to tell if sarcastic, but anyway. I think the GOTOers just died out. Some day null, statements (rather than expressions) and side-effects will have always been wrong.

knollimar 17d ago
No, they're not sarcastic. It was an interesting point; if an idea succeeds well enough people just do it and make it "common sense". It's a point in the talk.
tialaramex 17d ago
It's not the focus of the talk and so it's hard to tell if Casey understands (the choice to separate the words GO TO in several places suggests he does) but the `goto` keyword you've seen in several modern languages is not the problematic "GO TO statement", it's a de-fanged remnant, the toy poodle to GO TO's wolf pack. The actual GO TO complained of is, like the jump instruction in machine code, just entirely unbothered by context. Want to go from the middle of this code about employee payroll processing to mid-way through initializing a weather simulation? No problem. Well. No problem for the machine, for a human programmer it's a complete nightmare. Actually that's putting it mildly, nightmares have more structure. You cannot do anything like that with for example C's goto. You compiler can, and in a few cases (that's what the discussion about the tail-call optimisation is about for example) it will, but the program you wrote doesn't do this and so you don't have to try to keep the whole program in your head. So in that sense GOTO died out with, maybe BASICs? I think the BASICs tend to have that wolf nature GOTO feature, but nothing modern has it.
- cure_42 17d ago
  Windows batch, no?
  - tialaramex 17d ago
    COMMAND.COM in its batch mode? Kinda, sorta. The interpreter can AIUI "call" other files but the "goto" is restricted to the same file. So we can jump over a variable declaration which is pretty confusing, but we can't jump into unrelated code. Also while COMMAND.COM can't be as old as BASIC it must be pretty old.
- deleted 17d ago
  [deleted]
- hirvi74 17d ago
  So, I have never seen anyone actually use GOTOs, so maybe a lot of the stigma comes from excessive, poor usage or something. However, having written a good chunk of ASM in my life. I don't think jumps or branches are really that hard to follow. Jumps/Branches and GOTOs specify the next location. It is not as though one has to guess where. It's not the arrow, it's the archer that is the problem.
  - tialaramex 17d ago
    Never as in, in BASIC, or you've never seen goto in C? The de-fanged C "goto" is all over the place in Linux and in similar close-to-metal C software. C does not (yet, likely C2Y will fix this) have labelled break, so goto is used to say "I am inside a mess of nested loops, we're done, end the loops" and as a catch-all failure handler in some codebases. My guess is that your ASM is inflected by structured programming everywhere. Yes, unlike COME FROM we can see where we're going next with GO TO but if you go back 60+ years there is some scary code that even today's optimizers probably wouldn't emit because it's too crazy. Suppose calculate-total-fuel ends with three CPU instructions which copy register F into register H then add register C to it and multiply the sum by four. Over in locate-horizon it so happens we need to add two things together and multiply them by four and we could do that last. So, if those two things were in registers F and C we could just GO TO that last part of calculate-total-fuel. You're correct that we don't need to "guess where" it goes, but good luck understanding why the program works when it's like this, let alone the ordinary maintenance work of making small modifications.
    - AnimalMuppet 17d ago
      > My guess is that your ASM is inflected by structured programming everywhere. I think you're probably right. To expand on this: In asm, you can have things that are clearly functions. You have a stack discipline going in and out of them. They end with stack cleanup, then a RET or some such, which pops the return address off of the stack and jumps to it. Within that function, you have JMP instructions (or whatever) that move around within the function. You may also call other functions, by pushing variables on the stack, and then calling JSR or whatever to push the program counter on the stack and jump, and when those functions return, you'll be right where you were in this function. That's all sane, and it's "structured assembly". Non-structured assembly would be like the example in your second paragraph. You're in one function, and you JMP (not JSR) into the interior of a second function. Or, you simply don't have functions, just labels that you jump around do. That's not structured, and not sane.
- bogomog 16d ago
  In the early 90s I was doing IT type C with SQL database software. There was one pattern of goto usage common: clean up at the end of a function if something went wrong (close db cursor, log something, return error code, and the like). When that space went to Java and to some extent C++ (and later C#) exceptions could be used instead. A defer statement would have been a more direct replacement for the pattern, though.

by mrkeen 17d ago

Hard to tell if sarcastic, but anyway. I think the GOTOers just died out. Some day null, statements (rather than expressions) and side-effects will have always been wrong.

knollimar 17d ago

No, they're not sarcastic. It was an interesting point; if an idea succeeds well enough people just do it and make it "common sense". It's a point in the talk.

tialaramex 17d ago

It's not the focus of the talk and so it's hard to tell if Casey understands (the choice to separate the words GO TO in several places suggests he does) but the `goto` keyword you've seen in several modern languages is not the problematic "GO TO statement", it's a de-fanged remnant, the toy poodle to GO TO's wolf pack. The actual GO TO complained of is, like the jump instruction in machine code, just entirely unbothered by context. Want to go from the middle of this code about employee payroll processing to mid-way through initializing a weather simulation? No problem. Well. No problem for the machine, for a human programmer it's a complete nightmare. Actually that's putting it mildly, nightmares have more structure. You cannot do anything like that with for example C's goto. You compiler can, and in a few cases (that's what the discussion about the tail-call optimisation is about for example) it will, but the program you wrote doesn't do this and so you don't have to try to keep the whole program in your head. So in that sense GOTO died out with, maybe BASICs? I think the BASICs tend to have that wolf nature GOTO feature, but nothing modern has it.

cure_42 17d ago
Windows batch, no?
- tialaramex 17d ago
  COMMAND.COM in its batch mode? Kinda, sorta. The interpreter can AIUI "call" other files but the "goto" is restricted to the same file. So we can jump over a variable declaration which is pretty confusing, but we can't jump into unrelated code. Also while COMMAND.COM can't be as old as BASIC it must be pretty old.
deleted 17d ago
[deleted]
hirvi74 17d ago
So, I have never seen anyone actually use GOTOs, so maybe a lot of the stigma comes from excessive, poor usage or something. However, having written a good chunk of ASM in my life. I don't think jumps or branches are really that hard to follow. Jumps/Branches and GOTOs specify the next location. It is not as though one has to guess where. It's not the arrow, it's the archer that is the problem.
- tialaramex 17d ago
  Never as in, in BASIC, or you've never seen goto in C? The de-fanged C "goto" is all over the place in Linux and in similar close-to-metal C software. C does not (yet, likely C2Y will fix this) have labelled break, so goto is used to say "I am inside a mess of nested loops, we're done, end the loops" and as a catch-all failure handler in some codebases. My guess is that your ASM is inflected by structured programming everywhere. Yes, unlike COME FROM we can see where we're going next with GO TO but if you go back 60+ years there is some scary code that even today's optimizers probably wouldn't emit because it's too crazy. Suppose calculate-total-fuel ends with three CPU instructions which copy register F into register H then add register C to it and multiply the sum by four. Over in locate-horizon it so happens we need to add two things together and multiply them by four and we could do that last. So, if those two things were in registers F and C we could just GO TO that last part of calculate-total-fuel. You're correct that we don't need to "guess where" it goes, but good luck understanding why the program works when it's like this, let alone the ordinary maintenance work of making small modifications.
  - AnimalMuppet 17d ago
    > My guess is that your ASM is inflected by structured programming everywhere. I think you're probably right. To expand on this: In asm, you can have things that are clearly functions. You have a stack discipline going in and out of them. They end with stack cleanup, then a RET or some such, which pops the return address off of the stack and jumps to it. Within that function, you have JMP instructions (or whatever) that move around within the function. You may also call other functions, by pushing variables on the stack, and then calling JSR or whatever to push the program counter on the stack and jump, and when those functions return, you'll be right where you were in this function. That's all sane, and it's "structured assembly". Non-structured assembly would be like the example in your second paragraph. You're in one function, and you JMP (not JSR) into the interior of a second function. Or, you simply don't have functions, just labels that you jump around do. That's not structured, and not sane.
bogomog 16d ago
In the early 90s I was doing IT type C with SQL database software. There was one pattern of goto usage common: clean up at the end of a function if something went wrong (close db cursor, log something, return error code, and the like). When that space went to Java and to some extent C++ (and later C#) exceptions could be used instead. A defer statement would have been a more direct replacement for the pattern, though.