4 ms·

Re tuples, I guess you mean the multiple return values, and this assignment form: https://go.dev/play/p/vxm6lV7JS4z https://go.dev/play/p/vxm6lV7JS4z However h

Re tuples, I guess you mean the multiple return values, and this assignment form: https://go.dev/play/p/vxm6lV7JS4z https://go.dev/play/p/vxm6lV7JS4z However how would real first class tuples be an improvement in Go? Alef had them, and allowed various manipulations, as well as returning them, and passing them to functions. I note that they are present in Hare, but not present in Odin. Where the latter has the Go inspired multiple return values, but (AFAICS) no tuples, but does add tagged unions. Generally I'd not want to store a tuple, preferring a struct with named fields. So the only uses I can think of are those temporary ones for multiple return values and assignments, which are already covered.

rollcat 2y ago
My issue with Go's implicit tuples is similar to the pre-1.18 generics built into the language. We've had generic append since before 1.0, but it was "magical", you couldn't write your own generic append for e.g. a custom container. We've later managed to add generics in a way that didn't make append, make, etc seem out of place; but make remains a function with an optional, typed second parameter, IIRC the only one of its kind. The implicit tuples seem just as magical. You can have func f()(int, error), but a:=f() is an error. It's arguably better than Lua (which ignores the second value), but arguably loses to Python (which returns a proper, first-class tuple). Similar with destructuring. You can have g() struct{int;error}, but not i,err:=g() or struct{i, err} := g(). You can have f()(int, error), but again not a:=f(). You can have h(int, error) with h(f()), but that's a hardcoded special case, and somewhat unintuitive, since it violates x:=f(); h(x) - which would however hold in case of returning a struct. Go is just less composable, full of arbitrary exceptions and edge cases. (I do still love it though.)
- dfawcus 2y ago
  Sorry, but your response seems to be about consistency, or "purity" at some level. While what Go has may be inconsistent, what functional impact does that have? I can't see a need for 'de-structuring' as such, absent tuples. Even if it had real first class tuple types, like Alef did, what would one do with them? As I indicated, I'd not want to store them (other than holding in locals), prior to use. As I recall, Alef did support de-structuring with tuples, as well as re-structuring. One could assign either way between an unnamed tuple, and an 'aggr' (it's name for a struct). So at most I'd want to break them apart, which the return value thing gives. Hence if I was creating Go 2.0, I can't see why I'd want to add first class tuples, but could see a use for adding tagged unions.
  - rollcat 2y ago
    > Sorry, but your response seems to be about consistency, or "purity" at some level. > While what Go has may be inconsistent, what functional impact does that have? Same reasons why Go fixed C's: inside-out type declarations, function pointer syntax, ERRNO, headers, macros, signal handling, UB, all the things that technically had no "functional" impact but still directly contributed to consistency, ergonomics, clarity, ease of comprehension, and (either by proxy or directly) correctness. > I can't see a need for 'de-structuring' as such, absent tuples. Your playground example of a, b = b, a is not destructuring a tuple in action? It's basically the same syntax / mechanism as Python's destructuring assignment, which existed since before Go (except Python's was always more powerful). It's almost like you can do everything you want with a tuple in Go, except for actually holding it in your hand. > Even if it had real first class tuple types, like Alef did, what would one do with them? Similar things you'd do with a function without a name - work directly with the data at hand, without having to do the extra round trip to the attic to declare its name or shape. > Hence if I was creating Go 2.0, I can't see why I'd want to add first class tuples, but could see a use for adding tagged unions. That would probably break Go. I liked Chris Siebenmann's take on the subject: https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnionTypesComplexities https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnion... https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnionTypesAndZeroValues https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnion... https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnionTypesStartWithGoals https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnion... Meanwhile tagged unions bring you virtually all the way to ADTs, where pattern matching (generalised destructuring) is basically a must. (By the way, Python stumbled really badly when it added pattern matching without even having proper structs. It's almost comical, given def __init__(self, ...), that should've been gone as a part of the 3.0 break-the-world.)
    - dfawcus 2y ago
      > Similar things you'd do with a function without a name - work directly with the data at hand, without having to do the extra round trip to the attic to declare its name or shape. Note that in Alef, tuples are essentially a dual for an aggr, but with unnamed fields. So one always has to (explicitly, or implicitly via inference) declare its 'shape', in terms of number of members, and type of members. So one could declare: tuple (int, byte *, int) t; Then manipulate 't', one could also have a function return a tuple as in: tuple (int, byte *, int) something(int x) { /* ... */ } Then handle its return value either as: t = something(2); or byte *str; int value; (nil, str, value) = something(7); However the tuple 'shape' is always statically determined. Is that in your view satisfactory, or not? Or do you desires something where the tuple is an entirely dynamic type, sort of akin to syntax sugar on top of '[]interface{}'? More akin to the sort of dynamic thing which Python offers? Such that one can potentially have a program run, and each call to a given function returning a tuple may have different numbers of elements, potentially of different types within it. So that for said program, if the function return value depended upon input data, one could not determine the full set of tuples which may be returned?

rollcat 2y ago

My issue with Go's implicit tuples is similar to the pre-1.18 generics built into the language. We've had generic append since before 1.0, but it was "magical", you couldn't write your own generic append for e.g. a custom container. We've later managed to add generics in a way that didn't make append, make, etc seem out of place; but make remains a function with an optional, typed second parameter, IIRC the only one of its kind. The implicit tuples seem just as magical. You can have func f()(int, error), but a:=f() is an error. It's arguably better than Lua (which ignores the second value), but arguably loses to Python (which returns a proper, first-class tuple). Similar with destructuring. You can have g() struct{int;error}, but not i,err:=g() or struct{i, err} := g(). You can have f()(int, error), but again not a:=f(). You can have h(int, error) with h(f()), but that's a hardcoded special case, and somewhat unintuitive, since it violates x:=f(); h(x) - which would however hold in case of returning a struct. Go is just less composable, full of arbitrary exceptions and edge cases. (I do still love it though.)

dfawcus 2y ago
Sorry, but your response seems to be about consistency, or "purity" at some level. While what Go has may be inconsistent, what functional impact does that have? I can't see a need for 'de-structuring' as such, absent tuples. Even if it had real first class tuple types, like Alef did, what would one do with them? As I indicated, I'd not want to store them (other than holding in locals), prior to use. As I recall, Alef did support de-structuring with tuples, as well as re-structuring. One could assign either way between an unnamed tuple, and an 'aggr' (it's name for a struct). So at most I'd want to break them apart, which the return value thing gives. Hence if I was creating Go 2.0, I can't see why I'd want to add first class tuples, but could see a use for adding tagged unions.
- rollcat 2y ago
  > Sorry, but your response seems to be about consistency, or "purity" at some level. > While what Go has may be inconsistent, what functional impact does that have? Same reasons why Go fixed C's: inside-out type declarations, function pointer syntax, ERRNO, headers, macros, signal handling, UB, all the things that technically had no "functional" impact but still directly contributed to consistency, ergonomics, clarity, ease of comprehension, and (either by proxy or directly) correctness. > I can't see a need for 'de-structuring' as such, absent tuples. Your playground example of a, b = b, a is not destructuring a tuple in action? It's basically the same syntax / mechanism as Python's destructuring assignment, which existed since before Go (except Python's was always more powerful). It's almost like you can do everything you want with a tuple in Go, except for actually holding it in your hand. > Even if it had real first class tuple types, like Alef did, what would one do with them? Similar things you'd do with a function without a name - work directly with the data at hand, without having to do the extra round trip to the attic to declare its name or shape. > Hence if I was creating Go 2.0, I can't see why I'd want to add first class tuples, but could see a use for adding tagged unions. That would probably break Go. I liked Chris Siebenmann's take on the subject: https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnionTypesComplexities https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnion... https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnionTypesAndZeroValues https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnion... https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnionTypesStartWithGoals https://utcc.utoronto.ca/~cks/space/blog/programming/GoUnion... Meanwhile tagged unions bring you virtually all the way to ADTs, where pattern matching (generalised destructuring) is basically a must. (By the way, Python stumbled really badly when it added pattern matching without even having proper structs. It's almost comical, given def __init__(self, ...), that should've been gone as a part of the 3.0 break-the-world.)
  - dfawcus 2y ago
    > Similar things you'd do with a function without a name - work directly with the data at hand, without having to do the extra round trip to the attic to declare its name or shape. Note that in Alef, tuples are essentially a dual for an aggr, but with unnamed fields. So one always has to (explicitly, or implicitly via inference) declare its 'shape', in terms of number of members, and type of members. So one could declare: tuple (int, byte *, int) t; Then manipulate 't', one could also have a function return a tuple as in: tuple (int, byte *, int) something(int x) { /* ... */ } Then handle its return value either as: t = something(2); or byte *str; int value; (nil, str, value) = something(7); However the tuple 'shape' is always statically determined. Is that in your view satisfactory, or not? Or do you desires something where the tuple is an entirely dynamic type, sort of akin to syntax sugar on top of '[]interface{}'? More akin to the sort of dynamic thing which Python offers? Such that one can potentially have a program run, and each call to a given function returning a tuple may have different numbers of elements, potentially of different types within it. So that for said program, if the function return value depended upon input data, one could not determine the full set of tuples which may be returned?