To expand a little bit: I have found at least anecdotally that the benefits of a strong, rich type system are multiplicative with other features, not additive.

To expand a little bit: I have found at least anecdotally that the benefits of a strong, rich type system are multiplicative with other features, not additive. For example, types in Java are largely a nuisance. The type system lacks facilities to express obvious things (I want a list of things that all have this interface) in clean ways. Instead you have to resort to "clever" hacks which ultimately just circumvent the guarantees you wanted to establish. For small projects this is a non-issue. For large projects, this is hell. By contrast, type systems thrive in contexts with algebraic or sealed case types, or any form of pattern matching really. Or just plain old enums. In conjunction, these features enable very powerful static checks. Forcing you to handle None/Null/NONE/Nothing/nil cases everywhere encourages critical thinking. This introduces more issues, such as staircase code, but these are largely (I would personally say completely, and with a nice surplus) fixed by things like pipes, monads, computation expressions, and so forth. This extends to libraries as well. I can't count the number of times I've used libraries which changed their API's in "non-breaking" ways, such that certain functions returned types I assumed would never be returned. Was this my fault? Yes. But if the return type had been strongly typed and I had been working in such a language as described above then: 1) I would be forced to handle every extant constructor in that type. 2) If a new one was added, I'd get a compiler warning alerting me to the fact that I hadn't handled it (this is great!). 3) If the type changed entirely, I'd get an error warning me to the fact that my code was no longer compatible with the API provided. In the end, working with and writing libraries is about respecting contracts. Types are a tool for codifying those contracts. Strong typing and matching facilities are even more powerful tools for alerting you to violations.