On Thu, Jun 18, 2020 at 4:00 PM Bruno Albuquerque <b...@gmail.com> wrote: > > It looks to me one point of contention on using interfaces instead of > contracts is the fact that now interfaces have to support type lists but only > when used as contracts. This, no matter how you slice it, looks ugly. > > Now type lists are there to support built-in operations like operators in > general and range support. there is a finite (and relatively small) set of > combinations of types that make sense. > > Also there is already the intention of providing "contracts" like Comparable > in pre-existing libraries. > > There is also precedent for "magical" things in the language (range can > operate on slices of any type). > > So, with all that in mind, wouldn't it be possible for the language to offer > all the possible reasonable type combinations as built-in contracts in a way > that they could be embedded in other interfaces? They would be a bit magical > as their constraints are, under the hood, on types (not methods), but I guess > this would make things less ugly.
Thanks. It's not as easy as it sounds. There are many different type combinations in Go. It winds up being something like 25 new names to add to the language. That is a lot. Also, consider cases like https://go.googlesource.com/proposal/+/refs/heads/master/design/go2draft-type-parameters.md#composite-types-in-constraints . With those you get even more cases. It's likely that in practice the common constraints will be in a standard library constraints package, so relatively few people will write type lists. But the constraints package can be written in Go, which is nice, and people will be able to reach for complex cases with their own type lists when they need them, which is also nice. Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcUfvOLaOG_q%3DFgSWrSq9eA8z26Dj%2BCBKH6js23L5i2h8w%40mail.gmail.com.
