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Comment by dilap | Hacker News Reader

I feel like this specific issue Go just got wrong. 99% of the time you want a new variable in the range loop.

I think Go's strictness is very practical -- it's strict where they saw real problems and the cure was easy.

Something like threading race conditions is a real problem, but not easy to fix.

Go does give you a pretty good runtime tool with the race checker, though. It would quickly catch something like the fish bug of grabbing the wrong lock.

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>Something like threading race conditions is a real problem, but not easy to fix.

It is. It's called channels.

Sure, you could only use channels and you'd never get races, but in practice that'd be unwieldy and slow, which is why people write traditional lock-based sync stuff in Go all the time, and depend on old-fashioned debugging (and the race-checker).

Rust really fixes this (with its ownership system), but it wasn't easy.

>unwieldy and slow

So force one to do it consciously (kind of like unsafe).

> Sure, you could only use channels and you'd never get races

Go allows sending pointers to non-locked structures over channels, so it's quite easy to "only use channels" and still get race.

You can also hit that issue if you spawn multiple goroutines sharing the same initial lexical environment if they make use of a mutable structure from that environment.

If you're accessing mutable data from multiple goroutines, then you're not only using channels! :)

Of course you are. Go has essentially no support for immutable data structures, and even if you send large structures by value (which can get expensive) they themselves probably embed pointers to mutable data, and you're back at square one.

I didn't say it was a good idea (in fact, if you read far enough back up the comment chain, you'll see I was saying it's a bad idea), but you could, if you wanted to, restrict yourself to only communicating between goroutines via channels of immutable data and be confident that your code had no data races.

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