Comment by g15jv2dp

All of these have, at the very least, escape hatches that makes the type system unsound overall. And probably other issues https://counterexamples.org/ I can find a few in there for at least scala and haskell. Perhaps this is not a satisfying answer to you, an "unsound type system" is a technical, precise notion, and this is what people who parrot "typescript is unsound" are referring to. You cannot just reply "well there are a few runtime checks so it's all good."