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Comment by ben_jones | Hacker News Reader

IMO ruby is the worst because its so easy, and often times encouraged, to write layers of useless tests that ultimately give only a false sense of security. I recently re-did the Michael Hartl tutorial to catch up with Rails5 and it gives examples where you test proper template rendering. I love that book but I'd rather shoot myself in the foot then spend dev time writing tests to check if the right html title attribute was rendered for the page...

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Sometimes the right test is just occasional manual testing. And sometimes it's even just the fact that no users have complained about something obvious not being completely wrong.

Curious as to why you're blaming a language (ruby) for a bad practice (writing layers of useless tests). Excuse my pedantry, but it wouldn't it be more accurate to blame a culture that you feel has grown up around that language?

In Scala, "does it compile/typecheck" will generally catch typos in code that isn't frequently executed, and raise warnings for unhandled cases. For Ruby, you pretty much need to execute the code to have any inkling if it goes kaboom -- the language (and how people write it) have so much magic that short of executing things, the computer can't tell you anything useful.

Valid point.

I don't think I could write low-bug count code faster in statically typed scala than I could in unit tested ruby though. I mean I am well aware of what you're telling me, and it's obvious to me that having the compiler automatically check certain properties is a win. And yet, when push comes to shove, to get something done I'm more likely to reach for ruby.

It's something I've never come up with a good explanation for. Does static typing stunt prototyping and exploration? Do unit tests capture high level goals better?

I guess I don't agree with the assertion that ruby tests are useless. Because you test higher level things than you do with scala types.

"Does static typing stunt prototyping and exploration?"

Not in my experience. It is probably about what you personally find hard/uncomfortable/unfamiliar.

But you're kind of implying that I feel that way because either I don't use static typing much, or I haven't learned it well, aren't you?

I've used static typing much more than dynamic. I'll admit confusion on things like ocaml polymorphic variants and haskell monads, nevertheless I wouldn't say I find static typing hard as a rule. But surely the point of static type checking is to constrict what you can do for safety and performance reasons. And surely the cost of that is you have less freedom - even when in the exploration phase

"you're kind of implying that I feel that way because either I don't use static typing much, or I haven't learned it well, aren't you?"

No. I didn't mean to imply or assert anything of the sort. Apologies if I inadvertently gave offense. You seem to be reading meanings into my reply that aren't there.

I don't know you from Adam. You asked a question in your post. I answered as best as I could.

That said, your latest statement

"I'll admit confusion on things like ocaml polymorphic variants and haskell monads,"

does seems to imply that you don't have much real world experience with static type systems in production (nothing wrong with that) since neither is an arcane concept or particularly difficult to understand.

If you haven't worked extensively with Haskell/Ocaml/SML etc, and you are extrapolating properties of 'static type systems' from those of Java or C++ then your idea of such type systems 'stunt prototyping and exploration' might make sense.

The rest of your comments are extrapolations from misunderstandings - not born of practical experience. My answer was based on (strictly) personal experience. Which is why I said "in my experience". I gladly concede that YMMV.

again, I was just answering your question in your original comment. I didn't mean to "imply" anything and used "probably" to mark my uncertainty about your real world experience with Ocaml/Haskell etc style static type systems.

I have extensive experience with both dynamically typed languages (mostly Python, Lua and Scheme) and statically typed languages (mostly Haskell and SML, besides Java). I answered out of my experience.

YMMV. And that is cool.

I'm not offended. I am happy to talk to open minded static typing advocates. I myself am not really sure where I sit.

You're right, I haven't used ocaml or haskell in production. I did use F# though, which seems to be in the same ballpark as those languages in terms of having algebraic data types and inference and all the rest. I suppose the fact that I still don't really grok polymorphic variants after reading the real world ocaml a few times may say something about my ability, motivation, or at the very least how my brain is wired.

Fundamentally though, a type system is a restriction meant to help the programmer. This restriction must inevitably put you down a certain road when you explore stuff, right?

It depends on how often that freedom is used for a benefit rather than by accident and thus foot shooting.

It changes my approach to a problem, in that, with dynamic typing, I tend to think of problems as manipulating data, while with static typing I am modeling a domain, deseriazing data to it, and serializing the result. The end result usually ends up being a bit more verbose, but at the same time does a better job of holding my hand when the input format changes in the future. It's definitely a trade off though.

If you can achieve >90% testing, efficiently and properly. It's worth it. Testing for the correct title is worth it. Especially if the title has something appended to it at render time (i.e. hello | website_name). Someone can over ride this on a page and having a test to catch that is important. A well written test would check for page_name | website_name across all pages. Pages are finite. Such tests are useful. Hartl uses basic testing framework as an introduction but there are better ones available.

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