[_pmf_]

> Now what makes this little function so darn useful is it takes anything fulfilling its interfaces (io.Writer and io.Reader).

I've implemented InputStreams from byzantine transport layers in Java that work with the standard library. I don't quite understand what is special about this concept in Go (maybe it's nice for people coming from typeless, messy dynamic languages or nice languages with horribly inflexible and ad-hoc standard libraries like Python and Ruby).

[MetaCosm]

Go has nothing unique (and maybe that makes it special). I mean that sincerely, everything it has, has been done dozens of times. Interfaces in Go are implicit (which is important, IMHO) and really, tremendously simple. These two features make them exceptional easy to use, and ACTUALLY used.

I have used interfaces (or equivalent concepts) in dozens of languages and they always felt like far more of a chore, explicitly using X interface or Y interface, ugly complex declarative specs, etc. Go just makes it painless.

[LBarret]

replace Go with Python in the text, and you won't see a difference: there are iterable, keyable, file-like interfaces, etc. And creating your own is trivial.

[icebraining]

Yes, but Python doesn't compile to a single binary, and usually runs much slower.

What people like about Go is its mix of features, not some specific one by itself.

[pjmlp]

Depends on the implementation.

[cma]

Python doesn't verify the interface is met until run time.

[coldtea]

With all the cases were Go pushes you to use interface{} that's the case in Go a lot of the time too.

If it had Generics that would be another thing.

[ansible]

With all the cases were Go pushes you to use interface{} that's the case in Go a lot of the time too.

However, you can wrap an interface{} using container (for example), with type-specific input and output functions, getting back compile-time type-checking. Yes, it is not optimal, and yes, you're still paying the price for type assertions.

If it had Generics that would be another thing.

I would like to see a good solution for this that integrates well with the rest of the language.

[coldtea]

I would like to see a ho-hum solution for this that's on par with what's offered on other languages.

I say that because the Go designers, despite having designed a quite mediocre language, suddenly when it comes to generics the want the perfect no-compromises solution or nothing.

[jesstaa]

You can make an io.Reader interface in any language. Interfaces don't really shine until you start composing them.

Say you have a type that implements the io.Reader, io.Writer, io.Closer and io.Seeker interfaces, eg. an os.File. This type would also automatically implement io.ReadCloser, io.WriteCloser, io.ReadWriter and io.ReadWriteCloser, io.ReadSeeker, io.ReadWriteSeeker, io.ReadWriteSeekerCloser, io.WriteSeeker, io.SeekCloser etc.

[MetaCosm]

Yeah, I simply think that this is hard to explain in a comment how useful and easy it is. But, I gave it my best Go...