Your post can be pretty much answered with a big "no".

- No, we were talking about safety, not convenience. Stop shifting the subject. (But do you know what IS inconvenient? Being hit by a bug on production in your Ruby program that could have been prevented by a static type checker).

- No, this is not a case of No True Scotsman. First, you seem to misunderstand how fromMaybe is used (have you EVER programmed in Haskell?). Unlike other languages, where null can hit you by surprise, the programmer ALWAYS chooses the default value for fromMaybe. Since HE chooses it, it's not an accident. It can never happen by accident, as with null. Repeat after me: this. is. not. a. case. of. the. no. true. scotsman. fallacy. "So there is this Scottish guy..." "Wait, what if this is a Scotsman from Mars?" "But Scotsmen are from Scotland!" "A-HA! Fallacy!" This gets old fast.

- No, a programming language with additional safeties is logically safer than one without, all else being equal (i.e. if no other safeties get removed instead). Especially since those safeties don't prevent you from also applying every engineering practice from the other, no-safe language. You can do all the fancy testing you do for your Ruby programs in Haskell as well! In fact, a lot of interesting testing tools have come from the Haskell community, such as QuickCheck (aka property testing). In fact, it wouldn't surprise me if there was a RubyCheck nowadays.

- No, Haskell programmers aren't smug fools who believe that because their programs compile then they must be correct, and therefore no additional testing or QA is necessary. You keep bringing this old nonsense up, and you're the only one who believes it. Please accept as a given that no-one believes this and never bring it up again.

> What do you mean by "safer" here? Let's say "type-safety" means "a type-checker enforces some constraints" and "practical-safety" means "more likely to be correct, all else being equal". It seems you think "type-safety" == "safety" == "practical-safety", by definition.

Actually, rather than being equal, what I think is that an increase in one implies an increase in the other. A type-checker enforcing some constraints automatically makes your language practically safer than one without it. It's yet another tool in your toolset, one that gets automatically applied by the compiler. I get that, by convenience, some people want to write programs without some safeties; that's an issue of convenience, which is separate.

> Obviously, using a safety is not much effort. How much effort is required to satisfy the Haskell compiler?

Not much. Haskell programmers everywhere do it daily. What's your point? Have you written a program in Haskell and found it too hard?

Please think before you want to lecture me again about deductive and inductive reasoning. You sound condescending instead of clever.

I refuse to discuss this with you any further until you drop the sarcasm and answer this simple question: how fluent are you with Haskell? If you claim to have actual Haskell programming experience (tutorials don't count) I'll take your word for it, accept that you understand its trade-offs, and let you have whatever last word you want to have in this subject, and move on.