Comment by shevy-java
14 hours ago
Yeah. I have the same question and none of the type addicted folks could answer that. The explanations usually boil down to "I used C, so now I need types in other languages too". That's like 90% of the explanations you can see.
I have two genuine, straight forward answers for you. One, I have an important codebase written in a non-typed language, that is heavily developed still. So being able to add types to it (assuming I / team prefer that) is nice. Second is, I much prefer working in typed language, but company forces X language(s) (say, Ruby, Python, etc). Now I can use types (which I much prefer), and not change language (they prefer). Those are both real life examples. Third is hypothetical, but perhaps some people starting without types decide they like them later and want to dip their toes on. Most of these languages now offer incremental types for people to try them out.
Being able to retroactively apply type definitions to a system can be helpful for large legacy application refactoring where simply choosing a type-safe language is not an option.