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Comment by somewhereoutth | Hacker News Reader

However, there could be a really nice language emerging from the swamp.

Arrow notation, destructuring, functions as first class with underlying lambda calculus semantics (as opposed to lisp), async/await, back tick templating - strong features. Just need to get rid of the old cruft. Typescript and friends seem a good first step towards an implicit type system.

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>functions as first class with underlying lambda calculus semantics (as opposed to lisp)

Do you mind elaborating on this? How does lambda calculus underlie JS/TS functions but not functions in LISP?

The main issue is that LISP supports dynamic scoping, whereas lambdas act like lexically scoped functions.

Supports, but it's no longer the default for local variables. since 70s in Scheme and 80s in LISP.

Typescript is the way.

As a JS veteran who’s a newcomer to TS, it’s frequently mind blowing (so many user errors caught), but it is quite unwelcoming. The ‘tsserver’ errors are often useless, and the syntax feels arcane and terse.

I think I’ll probably get used to it, though.

I felt the same way at the start but I got used to it reasonably quickly. I already really appreciate its value even though right now I'm still basically a beginner.

Typescript only has compile time checking. There are so many sharp blades that allow that to be bypassed. For example, deserialize something into a variable you've declared to be a certain type, and viola. The typing is incredibly weak.

Most static languages only have compile-time type checking, because storing and checking runtime type information is usually not worth the cost. The problem with your example is the deserializer, which in a static language would be generated and include those runtime checks. I'm sure something like this exists for Typescript, it's too common a problem not to have been solved.

In Go, can I declare a Foo, and deserialize into it, but instead of a Foo, it is a Bar? No.

Typescript also doesn't catch cases where metaprograming is used when calling a function. You can put anything you want in there.

> For example, deserialize something into a variable you've declared to be a certain type, and viola.

I'm pretty sure your linter will catch this.

If you don't have a linter, get a linter.

this has been solved by several packages, runtypes https://github.com/pelotom/runtypes being my favorite

Thanks for the pointer to this, but this also makes Crockford's point about the need for a language that does this sort of thing and my point that in order to achieve safety, you need to know about such a package and manually employ the package. The compiler will not help you if you make a mistake in manually employing the package, or if you forget to use it, or if you don't know about it.

Have you seen the runtypes library? It lets you specify your type using a syntax very similar to normal TS type syntax. It then provides parsers for that type that throws errors if the input doesn’t conform to the type. It’s very useful. If anything, the library will impress you with how well it handles arbitrary types as well as how strong the TS type system is.

Please don't blame Viola for your careless deserializations.

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