Whats worth taking from "railroad oriented programming"

[monkyyy]

On Thursday, 27 February 2025 at 10:15:18 UTC, Bogdan wrote:
> On Friday, 21 February 2025 at 04:29:25 UTC, monkyyy wrote:
>> https://www.youtube.com/watch?v=srQt1NAHYC0
>>
>> The guy has nice pictures, but... I havnt seen it in a 
>> nonfunctional language
>>
>> In theory I want ranges + nullable to be smarter but; idk I 
>> dont know what to call it
>
> I tried to do something like that with this either monad 
> implementation. Have a look if you’re interested 
> https://github.com/gedaiu/either

Why does either have space for both values? Is that important?

```d
struct Either(T,S){
   T t;
   S s;
   bool which;
   ...
```

Shouldnt this by an alias of sumtype?
is either to pair as symtype is to tuple?