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One of the main motivations for adding generics is that we could then put typesafe algorithms and data structures in the standard library.
by bradfitz 8y ago
One of the main motivations for adding generics is that we could then put typesafe algorithms and data structures in the standard library.
- quotemstr 8y agoAnd make the standard library unmagical? One of the things I've always disliked about Go is how stdlib provides magic facilities unavailable to user code.
- icholy 8y agoWhat's magical about the stdlib?
- grey-area 8y agoMaybe they meant the language, which has some generic functions like append or delete - instead of those functions being attached to a data type or accepting any type, they only act on built-in types. I doubt any of that would change though given the stated goal of remaining compatible in most cases.
- SamWhited 8y agoThere are a handful of packages (time and some stuff in os for example) that are tied into the runtime and can't be rewritten outside the standard library. It's not a huge amount, and some of it can probably be fixed in the future.
- bradfitz 8y agoI agree, but there's not much, and it's usually for decent reasons: * the "time" package hooks into the Go scheduler. * the "reflect" package needs type information out of the runtime. * the "net" package hooks into the Go scheduler a bit. But way less than it used to. I think you might even be able to do this all yourself outside of std nowadays. What else? Our rough plan going forward is to actually move a bunch of the stdlib elsewhere but ship copies/caches of tagged versions with Go releases. So maybe "encoding/json" is really an alias for "golang.org/std/encoding/json" and Go 1.13.0 ships with version 1.13.0 of golang.org/std/encoding/json. But if you need a fix, feature, or optimization sooner than 6 months when 1.14.0 comes out, you can update earlier.
- aleksi 8y agoMy guess that quotemstr meant builtins: append, copy, range "protocol", etc.
- TheDong 8y agoThere are many examples of things builtins can do which user-code can't: 1. The constructs like "x <- chan" and "x, ok <- chan" (and map indexing and so on) are only available to builtin types. It's impossible to write a thing like "x, ok <- chan" where it either panics or doesn't depending on if the caller wanted two or one return values. 2. generic types, like 'map' and 'chan'. 3. 'len' can't be implemented for a user type, e.g. "len(myCustomWorkQueue)" doesn't work. 4. range working without going through weird hoops (like returning a channel and keeping a goroutine around to feed it) 5. Reserving large blocks of memory up front (e.g. as 'make' can do for slices and maps) in an efficient manner (e.g. make(myCustomWorkQueue, 0, 20) doesn't work)
- tptacek 8y agoYou're talking about the language. He's talking about the standard library.
- quotemstr 8y agoWe're both talking about both. The core of my complaint is that the language privileges parts of the standard library.
- TheDong 8y ago> privileges parts of the standard library It really doesn't. Maps and channels are not part of the stdlib. They're part of the language, but not the library. Similarly, range is part of the language, not the stdlib. If the stdlib was privileged, "container/*" in it would be generic, but it's not.
- quotemstr 8y ago
- deleted 8y ago[deleted]
- sdegutis 8y agoWhat changed? Why is the Go team finally considering this now, when it has been requested for these exact reasons by many credible developers since Go's beginning? EDIT: Yes, something has changed. They always said "no, but maybe later" and now it's "ok how about now". That is a big change and I am just asking what's the reason for it.
- m_sahaf 8y agoNothing changed. It wasn't off the table to begin with. See: https://golang.org/doc/faq#generics https://golang.org/doc/faq#generics
- coldtea 8y agoThe question of the parent boils down to "what put it on the menu". So, yeah, it was always "on the table" in some hazy, we'll see later, way, but not like that.
- BurningCycles 8y agoLikely because they have now figured out implementations of these features which they feel work well with the rest of the language design.
- sagichmal 8y agoI think a good faith reading of the circumstance would lead one to conclude that the passage of time, and other, higher-priority and lower-cost-of-implementation issues being addressed, have put these issues on the menu.
- cridenour 8y agoBecause now is later than when they said later?
- ianlancetaylor 8y agoA year ago we said it was time to move toward Go 2: https://blog.golang.org/toward-go2 https://blog.golang.org/toward-go2 . This is another step in that direction.
- tejasmanohar 8y agoWhat if generics were just implemented internally in Go? IMO, there are good use cases, like generic numbers (int32, int64, etc.), list processing, etc. There's already precedence for this with map[A]B, make(), etc.