[awused]

So you've defined idiomatic Go code in your own way, that no one else's definitions match with, such that no idiomatic Go code actually exists. If no idiomatic Go code exists, then it's definitionally true that all idiomatic Go code is without flaws, but I don't agree with your personalized definition of idiomatic Go in the first place.

>That may be true, but of no relevance.

So you agree with this, and it rebuts the entire contents of the first post I responded to. I wonder why you were posting irrelevant, off-topic content yourself. But I'm glad you finally agree that Go isn't flawless.

[randomdata]

> I don't agree with your personalized definition of idiomatic Go in the first place.

"That's the point. They are not equivalent, they represent different things" – Oh snap. Well, so much for that silly tangent.

If you want to actually have a discussion, you are going to have to go and understand the discussion that was taking place before you tried to take it in some weird and nonsensical direction. The non-sequitors may be entertaining, maybe even true, but off in la-la land with respect to the conversation taking place.

If your intent is simply to be my personal jester, then by all means, run with it. I'll continue to enjoy the laughs. Most people would pay good money to see an entertainer of this caliber, and you are offering it to me for free! I feel privileged.

[awused]

Since you seem unwilling or unable to follow an argument you started this seems more like an attempt to bait a response that you can report to the mods instead of an honest conversation. If you want to know why the alleged tangent was relevant, well, the posts are still there.

[Huggernaut]

Just in support of your position, the Google Style Guide says the following:

> If a function returns an error, callers must treat all non-error return values as unspecified unless explicitly documented otherwise

It is absolutely not idiomatic to give any meaning to non-error values under error conditions in the usual case. That is extremely unusual and would be generally confusing.

https://google.github.io/styleguide/go/decisions#returning-e...

[randomdata]

> It is absolutely not idiomatic to give any meaning to non-error values under error conditions in the usual case.

Based on what? We have come to see that it is beneficial to make zero values useful. In fact, Go Proverbs even says so. Likewise, we have learned it is useful to return the zero value when you have an error. Most commonly, this means returning nil, which is packed full of all kinds of useful information. Therefore, the T value can be expected to useful if the code is idiomatic.

I'd love to see some real-world code you think is idiomatic, but doesn't return a useful T value when there is an error.

> If a function returns an error, callers must treat all non-error return values as unspecified unless explicitly documented otherwise

This is not at odds with that. This merely warns that not all code you may call will be idiomatic. In fact, if I recall correctly, doesn't os.Open (maybe os.Create) return an invalid file handle in some error cases? The standard library is old and what helped us eventually see what is idiomatic. It is decidedly not idiomatic for the most part. If you rely on a function being written idiomatically, then you are going to run into trouble, as that is not a guarantee (unless the documentation provides such a guarantee).

But in the case of this Either wrapper, it explicitly states it is for use with idiomatic code, not any old code you can throw at it.

[awused]

>Based on what? ... In fact, Go Proverbs even says so.

And the Go style guide says otherwise: if err is non-nil, you shouldn't even check the other return values. The Go proverbs are just words, it doesn't make them true or even good ideas. When Go proverbs don't agree with how Go code is written, including idiomatic Go code, reality wins over a bad theory. The Go style guide happens to better match real code written by real people, even the people directly responsible for the proverbs.

>I'd love to see some real-world code you think is idiomatic

To be fair, I have been talking about the Go programming language and idiomatic code written in that language. You seem to have a different idea of "Idiomatic Go" from everyone else's. Most of the stdlib, including the newest additions, is idiomatic as judged by other people but evidently not by you.

[randomdata]

> if err is non-nil, you shouldn't even check the other return values.

Yes, it says you cannot trust functions, unless documented, to be idiomatic. Which is reasonable as not all code is idiomatic. The language goes to no lengths to enforce how the code is written in this regard (obviously). But we are talking about code that is known to be idiomatic.

> Most of the stdlib, including the newest additions, is idiomatic as judged by other people but evidently not by you.

1. I don't see how it could be. What is idiomatic emerges from writing code and seeing what works and what doesn't. Most of the stdlib was written in the early days before anyone understood what works best. And, thanks to the go1 guarantee, modifying it now is out of the question.

2. If you believe that the stdlib is idiomatic, then you have to accept that returning an int (-1) to represent an error is idiomatic. The standard library is full of that. Which violates the premise of FP-Go that (T, error) is idiomatic. That is not my claim, that is theirs.

[awused]

>Yes, it says you cannot trust functions, unless documented, to be idiomatic.

That is not what it says, in fact, it almost says the opposite. It is idiomatic Go to never return useful values if error is non-nil unless explicitly documented. It never affirms your particular, personal, definition of what "Idiomatic Go" is and directly contradicts it.

>If you believe that the stdlib is idiomatic

I believe most of the stdlib is idiomatic Go, especially the newer stuff. Your excuse earlier was that the older stuff in the stdlib isn't idiomatic but the newer stuff is. But the newer stuff doesn't match your personal standards for being idiomatic either. I would challenge you to point to a large body of code that actually matches your definition of idiomatic, I do not think it exists.

[randomdata]

> It is idiomatic Go to never return useful values if error is non-nil unless explicitly documented.

No, it is very much written from a consumer perspective. There is known, non-idiomatic, code where relying on T in its error state is problematic, so the guidance is reasonable and logical.

But we're talking about this from the producer perspective. These do not challenge each other and can exist in harmony.

> believe most of the stdlib is idiomatic Go, especially the newer stuff.

I wholeheartedly agree, at least with respect to the newer stuff, and have already said as such. Now this is where, in that newer work which is idiomatic, you point to a good example of where you can find meaningless return values when there is an error.

Clearly the vast majority of the standard library, especially in the newer stuff, does return meaningful values upon error, so we need to identify those which buck the trend if we want to hold it as a counterexample of this being an idiomatic practice.