Dan Vanderkam

_Comment by **danvdk** on **2021-04-12 09:19**:_ Interesting article. Reading it, I'd actually guess that pushing null values to the perimeter of your types would be a perf win, since it...

_Comment by **Serhii** on **2021-04-12 10:54**:_ I don't have numbers. But some time ago, I made small research in nodejs with help of V8 built ins. Every js object gets...

_Comment by **Serhii** on **2021-04-12 10:56**:_ Btw, I learnt a lot from your book, it is a gem. Thanks you!

_Comment by **Tamás Hegedűs** on **2022-01-25 12:51**:_ Great article! I would disagree with this statement:How often does this occur? Surprisingly rarelyIf you came with a static typed language background, then...

_Comment by **danvdk** on **2022-02-06 03:43**:_ Thanks! My point is just that, putting my paranoid hat on, I'd expect to run into inaccurate types from third-party libraries all the time....

@tylim88 Thanks for pointing me at Dart, I hadn't read about it in quite a while. The [Dart language guide](https://dart.dev/guides/language/type-system) provides a definition for unsoundness: > What is soundness? >...

_Comment by **disqus_0l6QhEp9JS** on **2020-11-28 03:11**:_ "A final case that triggers this "evolving any" behavior is if a variable is initially null. This often comes up when you set a...

_Comment by **danvdk** on **2020-11-28 10:02**:_ Gah, should be fixed now, thanks for the heads up. (This broke along with a few other things as a result of incorporating literate-ts...

_Comment by **disqus_0l6QhEp9JS** on **2020-11-29 07:02**:_ No problem! Looking forward to reading the book now :)

@arvabalazs interesting question. Neither of those declarations is quite the same. For this declaration: ```ts declare function getUrl(path: keyof API, params: ExtractRouteParams): string; ``` is that `typeof path` is just...