8 ms·

~= and 1-indexing are only weird if you haven't seen them before. MATLAB uses them as well.

by ebg13 6y ago

sk0g 6y ago
Isn't "weird == not seen it before" anyway? I get what you're trying to say, but MATLAB is not really a programming language SWEs would use, so if that's the best example you can think of, Lua's bound to confuse most people in the industry. May work better for mathematicians, non-SW engineers etc, but I wouldn't know.
- rpdillon 6y ago
  Julia is 1-indexed as well.
  - luhn 6y ago
    Which is also targeted towards scientific computing.
- ebg13 6y ago
  > I get what you're trying to say, but MATLAB is not really a programming language SWEs would use It may not be a language that website jockeys use, but "I don't use it therefore probably no one does" is almost never correct. MATLAB is huge in state machine and dynamic systems programming as well as being the original commercial powerhouse for linear algebra algorithms.
  - sk0g 6y ago
    I meant to say most SWEs, which you seemed to have inferred anyway. Why do you think that's wrong? I simply claimed MATLAB is much more commonly used by scientists and non-SW engineers. Most SWE jobs are in B2B, web development, embedded, etc fields. Which one of these sees a lot of MATLAB usage? Maybe don't resort to insults straight away too.
    - ebg13 6y ago
      > Most SWE jobs are in B2B, web development Citation? > embedded, etc fields. Which one of these sees a lot of MATLAB usage? Both embedded and etc. MATLAB is used widely in signal processing and controls software. > Maybe don't resort to insults straight away too. Sorry. I get annoyed when someone pretends that Software==Websites as if any of our trusted electronics are designed or programmed in javascript.
- deleted 6y ago
  [deleted]
jontro 6y ago
The tilde ~ char is pretty annoying to type on swedish keyboards at least. Alt + ¨ and a space on my mac. Having to type this regularly on my main languages would be off putting
deathanatos 6y ago
It's not just weird, or different, though; there are reasons to prefer 0-based indexing: https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD831.html https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/E...
- curtisf 6y ago
  I really don't like seeing this cited as a "proof" that 0-based indexing of lists is better. It is too shallow and ignores too many important facets of the question. The main contrast Dijkstra is drawing is between closed and half open intervals. Typically, the choice "starting from one" is tied to "closed" intervals, but that's not strictly necessary. Nothing stops you from using half-open intervals on Lua lists any more than you can used closed intervals to index into C arrays. The main advantage of the typical coupling is avoiding `+`s and `-`s in your "typical" loops over the first n indices: for i = 1, n do -- closed for (int i = 0; i < n; i++) { // half open but what if you want to go in reverse? Getting the _final_ indexes requires arithmetic with half-open intervals, but it doesn't with closed (which also requires changing the operator from exclude-eq to include-eq): for i = n, 1, -1 do -- closed for (int i = n - 1; i >= 0; i--) { // half open Of course, probably the most important property of half-open intervals is the way that they can be broken down into two disjoint intervals: `[A, C) = [A, B) U [B, C)`. But if your indexes are integers this is straightforward with closed intervals too: `[A, C] = [A, B - 1] U [B, C]` or `[A, C] = [A, B] U [B + 1, C]`. But again, if you're using this property, you probably don't actually care about the "absolute" indexes at all; indexing with `[1, #list + 1)` isn't a problem _at all_ in Lua. Plus, between the operations of "get final index" and "split interval into non-overlapping pieces", "get final index" is far more common (it's crucial to stacks, queues, etc, in addition to various uses like iterating backwards). Choosing "closed" intervals is then the cleaner option to avoid an ugly "+" or "-"! Dijkstra mentions that requiring -1 to refer to an initial interval as "ugly" since -1 is not a valid index, but he has no qualms with using the length of the list, n, and allowing it to not be an index! This is all said without even going into the awkwardness of having [k] being the {k+1}th element (e.g., [4] is how we write "fifth" in C -- I distinctly remember at least one conversation at work where the wrong thing was communicated because someone said "fourth" to mean [4]) Now, don't take this as a serious argument that 0-indexed-lists are inferior to 1-indexed lists. It's just a demonstration that it's easy to argue either side. That's because it's really just an unimportant convention. Pick one and stick with it and everything will work fine, modulo confusion about what "fourth" means.
samatman 6y ago
I work with Lua extensively, including abstract syntax trees. To mark a node at the third position, containing one character, we say {3,3}. But what if there's a node at the third position, that contains no character? Well, thats {3,2}. It's like nails on a chalkboard every time. 1-based indexing is a mistake. ~=, by contrast, is just notation. You get used to it quickly.
- saagarjha 6y ago
  > To mark a node at the third position, containing one character, we say {3,3}. > But what if there's a node at the third position, that contains no character? Well, thats {3,2} Why not shift over indexing by one consistently? So you'd use {3, 4} and {3, 3} for each, so the length property is preserved.
  - samatman 6y ago
    Because that's not how the string library works. ("12345"):sub(3,3) returns "3", while ("12345"):sub(3,4) returns "34", and ("12345"):sub(3,2) returns "". Indexing in the array portion of tables, and strings, is at least consistent; but Djikstra was right. The Wiki[0] has a good discussion of Djikstra's iconic essay. The best of these arguments, imho: 0 based indexing unifies enumeration and measurement. [0]: https://wiki.c2.com/?WhyNumberingShouldStartAtZero https://wiki.c2.com/?WhyNumberingShouldStartAtZero
- int_19h 6y ago
  That's an argument against end-inclusive ranges more so than against 1-based indexing. If they were end-exclusive, like in Python, then {3,3} would be an empty string, and {3,4} would be a single character at 3. Note how it suddenly doesn't matter at all whether the indices are 0-based or 1-based - all of the above is valid regardless. FWIW, I think that the real mistake was to make inclusivity/exclusivity implicit to begin with. If the syntax is explicit, and the choice is captured in the resulting value (i.e. it's more than just a pair of numbers), then you just use whatever is more convenient for the task at hand. Nim almost gets there: (x .. y) is end-inclusive, and (x ..< y) is end-exclusive - but the syntax still exhibits a preference.

~= and 1-indexing are only weird if you haven't seen them before. MATLAB uses them as well.

by ebg13 6y ago

~= and 1-indexing are only weird if you haven't seen them before. MATLAB uses them as well.

sk0g 6y ago

Isn't "weird == not seen it before" anyway? I get what you're trying to say, but MATLAB is not really a programming language SWEs would use, so if that's the best example you can think of, Lua's bound to confuse most people in the industry. May work better for mathematicians, non-SW engineers etc, but I wouldn't know.

rpdillon 6y ago
Julia is 1-indexed as well.
- luhn 6y ago
  Which is also targeted towards scientific computing.
ebg13 6y ago
> I get what you're trying to say, but MATLAB is not really a programming language SWEs would use It may not be a language that website jockeys use, but "I don't use it therefore probably no one does" is almost never correct. MATLAB is huge in state machine and dynamic systems programming as well as being the original commercial powerhouse for linear algebra algorithms.
- sk0g 6y ago
  I meant to say most SWEs, which you seemed to have inferred anyway. Why do you think that's wrong? I simply claimed MATLAB is much more commonly used by scientists and non-SW engineers. Most SWE jobs are in B2B, web development, embedded, etc fields. Which one of these sees a lot of MATLAB usage? Maybe don't resort to insults straight away too.
  - ebg13 6y ago
    > Most SWE jobs are in B2B, web development Citation? > embedded, etc fields. Which one of these sees a lot of MATLAB usage? Both embedded and etc. MATLAB is used widely in signal processing and controls software. > Maybe don't resort to insults straight away too. Sorry. I get annoyed when someone pretends that Software==Websites as if any of our trusted electronics are designed or programmed in javascript.
deleted 6y ago
[deleted]

jontro 6y ago

The tilde ~ char is pretty annoying to type on swedish keyboards at least. Alt + ¨ and a space on my mac. Having to type this regularly on my main languages would be off putting

deathanatos 6y ago

It's not just weird, or different, though; there are reasons to prefer 0-based indexing: https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD831.html https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/E...

curtisf 6y ago
I really don't like seeing this cited as a "proof" that 0-based indexing of lists is better. It is too shallow and ignores too many important facets of the question. The main contrast Dijkstra is drawing is between closed and half open intervals. Typically, the choice "starting from one" is tied to "closed" intervals, but that's not strictly necessary. Nothing stops you from using half-open intervals on Lua lists any more than you can used closed intervals to index into C arrays. The main advantage of the typical coupling is avoiding `+`s and `-`s in your "typical" loops over the first n indices: for i = 1, n do -- closed for (int i = 0; i < n; i++) { // half open but what if you want to go in reverse? Getting the _final_ indexes requires arithmetic with half-open intervals, but it doesn't with closed (which also requires changing the operator from exclude-eq to include-eq): for i = n, 1, -1 do -- closed for (int i = n - 1; i >= 0; i--) { // half open Of course, probably the most important property of half-open intervals is the way that they can be broken down into two disjoint intervals: `[A, C) = [A, B) U [B, C)`. But if your indexes are integers this is straightforward with closed intervals too: `[A, C] = [A, B - 1] U [B, C]` or `[A, C] = [A, B] U [B + 1, C]`. But again, if you're using this property, you probably don't actually care about the "absolute" indexes at all; indexing with `[1, #list + 1)` isn't a problem _at all_ in Lua. Plus, between the operations of "get final index" and "split interval into non-overlapping pieces", "get final index" is far more common (it's crucial to stacks, queues, etc, in addition to various uses like iterating backwards). Choosing "closed" intervals is then the cleaner option to avoid an ugly "+" or "-"! Dijkstra mentions that requiring -1 to refer to an initial interval as "ugly" since -1 is not a valid index, but he has no qualms with using the length of the list, n, and allowing it to not be an index! This is all said without even going into the awkwardness of having [k] being the {k+1}th element (e.g., [4] is how we write "fifth" in C -- I distinctly remember at least one conversation at work where the wrong thing was communicated because someone said "fourth" to mean [4]) Now, don't take this as a serious argument that 0-indexed-lists are inferior to 1-indexed lists. It's just a demonstration that it's easy to argue either side. That's because it's really just an unimportant convention. Pick one and stick with it and everything will work fine, modulo confusion about what "fourth" means.

samatman 6y ago

I work with Lua extensively, including abstract syntax trees. To mark a node at the third position, containing one character, we say {3,3}. But what if there's a node at the third position, that contains no character? Well, thats {3,2}. It's like nails on a chalkboard every time. 1-based indexing is a mistake. ~=, by contrast, is just notation. You get used to it quickly.

saagarjha 6y ago
> To mark a node at the third position, containing one character, we say {3,3}. > But what if there's a node at the third position, that contains no character? Well, thats {3,2} Why not shift over indexing by one consistently? So you'd use {3, 4} and {3, 3} for each, so the length property is preserved.
- samatman 6y ago
  Because that's not how the string library works. ("12345"):sub(3,3) returns "3", while ("12345"):sub(3,4) returns "34", and ("12345"):sub(3,2) returns "". Indexing in the array portion of tables, and strings, is at least consistent; but Djikstra was right. The Wiki[0] has a good discussion of Djikstra's iconic essay. The best of these arguments, imho: 0 based indexing unifies enumeration and measurement. [0]: https://wiki.c2.com/?WhyNumberingShouldStartAtZero https://wiki.c2.com/?WhyNumberingShouldStartAtZero
int_19h 6y ago
That's an argument against end-inclusive ranges more so than against 1-based indexing. If they were end-exclusive, like in Python, then {3,3} would be an empty string, and {3,4} would be a single character at 3. Note how it suddenly doesn't matter at all whether the indices are 0-based or 1-based - all of the above is valid regardless. FWIW, I think that the real mistake was to make inclusivity/exclusivity implicit to begin with. If the syntax is explicit, and the choice is captured in the resulting value (i.e. it's more than just a pair of numbers), then you just use whatever is more convenient for the task at hand. Nim almost gets there: (x .. y) is end-inclusive, and (x ..< y) is end-exclusive - but the syntax still exhibits a preference.