tuple not part of core language

[Julian Fondren]

On Monday, 19 January 2026 at 20:03:28 UTC, monkyyy wrote:
> On Monday, 19 January 2026 at 15:53:45 UTC, DLearner wrote:
>> Hi
>> Is there some reason why tuples are not part of the core 
>> language (like, say, struct, which to me is v.similar) but has 
>> to be pulled in via ```import std.typecons;```?
>
> its a 30 year old code base, whats in there isnt cleanly mapped 
> to theory

OCaml also has a 30-year-old code base and has had tuples for 
that long, but it's a different language with different goals, 
design constraints, and inspirations. Which is the answer to the 
original question: tuples are provided by a library because D 
isn't of a language family that cares much about tuples. The 
usual syntax would also conflict with C's comma operator, 
although D now mostly treats it as an error:

```d
writeln(1), writeln(2); // ok
writeln((1, 2)); // using the result of a comma expression is not 
allowed
1, writeln(2); // `1` has no effect
```

OCaml:

```ocaml
# #require "fmt";;
# Format.printf "%a\n" Fmt.int 1, Format.printf "%a\n" Fmt.int 2;;
2
1
- : unit * unit = ((), ())
# Format.printf "%a\n" (Fmt.Dump.pair Fmt.int Fmt.int) (1, 2);;
(1, 2)
- : unit = ()
# 1, Format.printf "%a\n" Fmt.int 1;;
1
- : int * unit = (1, ())
```

For 30 years D has had function overloading that lets it use just 
`writeln()` with whatever types you give it, whereas to get even 
this close to a similar example OCaml needs two high-powered 
libraries and this verbose reconstruction of the provided type. 
Can this be explained as "its a 30 year old code base, whats in 
there isnt cleanly mapped to practice"?