[dmitriid]

> How is the compiler catching your logic bugs?

It doesn't, and I agree with your sentiment. IIRC, type-related errors account for ~10% of bugs.

If (and only if) types are tied into your tooling ecosystem (for example, an IDEs that uses that info to full extent to aid in code completion, refactoring, code analysis etc.), they are very useful.

[b_t_s]

> type-related errors account for ~10% of bugs.

This sounds implausible to me unless they're only counting bugs that have slipped through QA and have later been fixed in production. In my experience the compiler catches maybe 95% of my errors I write. Most of those would be caught by my unit tests or my manual testing, and a few more would be caught by the QA team, but it's much nicer and faster to get notified about them immediately.

[neillyons]

> It doesn't, and I agree with your sentiment. IIRC, type-related errors account for ~10% of bugs.

I never thought of that, but that is a really valid point. I guess that is why Ruby/Python are so popular as most of the problems programmers run into in production aren't type problems.

[jasone]

Type correctness is pure power, or a waste of time, depending on... perspective! I can't help thinking back to the highly illustrative example of my first enhancement to Facebook's production website as a "bootcamper" in 2009.

I was tasked with adding proper honorifics for Japanese speakers (it's complicated in the general case, but I was just getting as far as "San"). I wrote some straightforward PHP code to implement this feature, but of course it broke in production for some nontrivial percentage of requests. Why? Because the string I was adding the honorific to wasn't always a string. WTF? What is the proper course of action when strings aren't strings? Well, in this case the answer was a run-time type-check guard on the code I had added.

Keith Adams, my esteemed colleague, likened this to "dogs and cats living together", perhaps revealing a fondness for simpler days when Ghostbusters trod the streets. Keith may not have gone as far as lauding OCaml's type system in those dark early days, but I will do so now (and perhaps he would too).

[xfer]

That is not why these languages are popular. Types are your design document in languages with expressive type system. So by design you can make it hard to make logical errors.