Hacker News Reader

Comment by karmakaze | Hacker News Reader

It's no surprise. The example is ignoring the error from casting. It should be:

  if quacker, ok := duck.(interface { Quack() }); ok {
    quacker.Quack()
  }

Ignoring errors leads to unexpected results.

Failing to mention that it's purposely ignoring an error for a fun blog post is the opposite of informative.

View on HN

But it mentions exactly this after the page break?

Right it mentions it when casting to Duck. The post makes it read like casting to `interface { Quack() }` was a problem, when really it was the ignoring of the error return value from that cast.

The language shouldn’t let you silently ignore errors.

It's not silent. It will panic.

but that'll be at runtime

In Go, a runtime panic indicates a programmer error. This means you should not have written that line of code. The solution is to fix the line of code.

Every languages let you ignore errors, Rust included.

The fact that the error happens _at run time_ is exactly the point. Whether the error is handled or not has nothing to do with the point of the post.

I didn't think anyone was under the impression that Go (or Java, or many other statically-typed languages) have sound type systems. For better/worse there are often intentional and unintentional escape hatches.

Go also has an 'unsafe' package that can mess things up at runtime--don't do that and don't ignore errors.

that an who the fuck uses interface literals? I do Go personally and professionally for years and never seen it.

I was about to say, after so many years doing Go, I have never seen this and would love to read blog post about why interface literal is useful.

You can learn from the Go codebase to get a feel of why this is useful:

https://github.com/golang/go/blob/master/src/cmd/go/internal... https://github.com/golang/go/blob/master/src/io/fs/fs.go#L26... https://github.com/golang/go/blob/master/src/errors/wrap.go#... https://github.com/golang/go/blob/master/src/go/parser/resol...

If the interface check fails, does the code panic or does the `ok' value just get set to false?

If `ok' gets set to false, that seems optimal. Pretty neat, in fact, what other language permits such low-key, easy runtime interface checks?

this will panic:

v := hello.(world)

this never panic:

v, ok := hello.(world)

and yes, its awesome. people rag on Go because BLARG ERRORS BOILERPLATE, but if you can get over that Go is not Python/JavaScript, you're left with a simple powerful language

The Go standard library uses it. I didn't suss out the reason for it though.

An example is in the errors package: https://cs.opensource.google/go/go/+/refs/tags/go1.23.0:src/...

Reply on news.ycombinator.com