What, apart from string reverse, do you miss for real projects?
First, it has a lot of useless packages you typically wouldn't use, like "log" and "flag" (which work, but are way worse than third party alternatives like logrus and pflag), but also like "syscall" (as it says 'deprecated, use 'golang.org/x/sys' instead), "image/draw" (nope, you wanted 'golang.org/x/image/draw' usually), "path" for working with paths (you wanted "filepath"), "net/rpc" and "rpc/jsonrpc", "plugin" (almost always a bad idea), a chunk of "strings" (use "golang.org/x/text" for proper unicode support) and so on. Some of those are marked deprecated, most of them are not, and are just waiting for someone to accidentally use them.
That's issues I have with the stdlib and not stuff I'm missing though... Though I guess I really do miss a good logging library, or at least interface for external packages to implement so I can plug in logging libraries without rewriting the world.
One thing I do find missing frequently is a reasonable set type with the ability to do things like basic set operations (intersect, diff, etc). I constantly have to write ad-hoc for loops in go to do set operations, and it's verbose, non-obvious what the code does, and easy to get wrong.
But honestly, the main thing I'm missing isn't actually a package, but more about error handling for the stdlib as a whole, which is more a language issue. I really wish I could know what possible errors stdlib functions returned without, fairly often, having to read huge chunks of stdlib code to determine that.
Perhaps 40% of the stdlib documents the error type it returns in a message (like 'os.Chdir' always returns '*os.PathError'), but for the rest, good luck. Want to figure out what errors you might have to check for 'tar.Writer.Close()'? Well, the docs says "returns an error", the interface is "error", you have to read hundreds of lines of code to figure out the possible concrete types it could be. Maybe 15% of the time, you end up having to string-match on error messages because the error var or type is unexported.
Well, it's structural, so you don't need other packages to implement an interface rather you need them to accept an interface. That also makes it clear it's a bigger ask - you're not asking a dependency "please also do X" but instead asking "please never need to more than Y".
> Want to figure out what errors you might have to check for 'tar.Writer.Close()'? Well, the docs says "returns an error", the interface is "error", you have to read hundreds of lines of code to figure out the possible concrete types it could be.
The concrete types it could be are unbounded, because `tar.Writer` wraps arbitrary `io.Writer`s. If you need multi-pathed error handling (usually people don't and are just making it out of habit!), worry about what things can do, not what they are.
When I'm looking at an error, it's typically for one of two reasons:
1. To set a correct status code, such as http 5xx (internal server error, our disk flaked) or a 4xx (user error, you gave us invalid input).
2. To provide a better error message, such as to localize it into an error string.
If you're building CLI tools for yourself, sure, every error is fatal and you can read english so you don't need either of those. For most go projects, both of those are relevant concerns for a large number of error paths.
Go's type-system does not help you at all.
Speaking of...
> Well, it's structural, so you don't need other packages to implement an interface rather you need them to accept an interface. That also makes it clear it's a bigger ask - you're not asking a dependency "please also do X" but instead asking "please never need to more than Y".
Yup. That is a big problem. That's the root of the error problem too, where every package returns the stdlib error interface, which is a tiny subset of what you usually want.
- Do you want to reverse bytes, or codepoints?
- Do you want to reveres codepoints, or grapheme clusters?
- Do you really want to reverse grapheme clusters, or do you want to reverse some grapheme clusters while leaving e.g. sequences of control characters in the same order?
- Do you really want to reify any of this rather than iterate backwards in the existing memory?
C++: reverse(str.begin(), str.end());
Dart: str.split('').reversed.join();
Java: new StringBuilder().append(str).reverse().toString();
JavaScript: str.split('').reverse().join('');
PHP: strrev($str)
Python: ".join(reversed(str))
Rust: str.chars().rev().collect()
(What do I mean by wildly different things?
C++: Swaps the string's contents in-place, and probably breaks any multi-byte code units unless you've got a parameterized std::string at hand.
Dart: Makes a new string but has to round-trip via an array, because... it doesn't have a string reverse? This seems like a really bad argument for your side!
Java: Reverses codepoints, but the fact you have to round-trip through a StringBuilder to handle this is also telling.
JavaScript: Same comments as Dart, but I believe this is broken, it will reverse surrogate pairs incorrectly.
PHP: Good luck figuring out what this does depending on your platform, locale, and moon phase.
Python: Another codepoint reverse, again not via strings but a lazy sequence, and also not even idiomatic - use `str[::-1]`.
Rust: And finally again... not a string reverse.
You want a Go slice reverse? You can get a perfect one post-generics.)
