9 ms·

Props to the implementor for sure, but I dunno, if a specification is supposed to solve a problem in a very limited niche, but can actually do something like th

Props to the implementor for sure, but I dunno, if a specification is supposed to solve a problem in a very limited niche, but can actually do something like this, I feel like the spec is actually _too_ flexible. I feel the same way about "Quake implemented in CSS" demos. Like, very cool, but you actually should not be able to do that...

jonahx 3y ago
I believe in both cases the Turing completeness is accidental, and in the case of CSS a security concern. (In the case of TS, see https://github.com/microsoft/TypeScript/issues/14833 https://github.com/microsoft/TypeScript/issues/14833) If anyone has more historical evidence that this is so for CSS, reactions from original authors, etc, or further evidence in the case of TS, I'd be curious to see it.
- Dylan16807 3y ago
  Security concern how? Also CSS can't iterate so it's just at the level of arithmetic.
Kinrany 3y ago
Any sufficiently advanced type system necessarily becomes Turing complete because type systems generalize to full compile time programming
IshKebab 3y ago
There isn't really any advantage of artificially limiting the power of type systems. Yes you shouldn't implement Flappy Bird in a type system... but just don't do that. This is obviously for fun.
jlfsdlkj 3y ago
If you ever wrote any JS pre-typescript and then switched to typescript, I do not think you would call the problem "very limited niche."
nicoburns 3y ago
If you think about it, then it makes quite a lot of sense that a type system aiming to describe the behaviour of a dynamically typed language would end up being this powerful.
- taneq 3y ago
  Having recently finished I Am A Strange Loop, I'm starting to think it's harder for any formal system to not be Turing-complete than it is for it to be so.
tshaddox 3y ago
For TypeScript I'm not really sure what you would expect them to change just to avoid being Turing complete. Its Turing completeness is a straightforward consequence of its basic building blocks: iteration, conditional types, and recursive type definitions. Of course TypeScript could go out of its way to avoid Turing completeness by just specifying a maximum recursion depth or something similar, but why?
- RussianCow 3y ago
  > specifying a maximum recursion depth or something similar Doesn't TS do exactly this? It doesn't seem like setting a cap on recursion depth would disqualify something from being Turing complete. Or am I misunderstanding your comment?
  - explaininjs 3y ago
    When recursion is the only method of iteration, of course it would.
    - smacke 3y ago
      Is the recursion limit an implementation detail of the compiler though, or something statically built into the language? If the former there's nothing to prevent the language itself from being Turing complete. (Similar to how every Turing complete programming language today runs on something technically weaker than a Turing machine due to finite memory.)
      - explaininjs 3y ago
        There’s no spec so the compiler is the language.
    - olalonde 3y ago
      What is the other method of iteration? Also, TypeScript does have a recursion limit[0]. [0] https://herringtondarkholme.github.io/2023/04/30/typescript-magic/ https://herringtondarkholme.github.io/2023/04/30/typescript-...
deleted 3y ago
[deleted]
a_wild_dandan 3y ago
Why? What benefits would we maybe gain by weakening TypeScript?
_gabe_ 3y ago
Isn’t every programming language simply a spec? C and C++ are infamous for just being a spec, with lots of undefined portions resulting in undefined behavior. And if every programming language is a spec, should we inhibit the flexibility of what you can do in them? (I think the answer here is no, but maybe there’s a good reason for limiting what you can do) Edit: Additionally, it takes very little to define a specification that leads to emergent behavior. That’s not necessarily a bad thing. It’s been awhile, but all you need for a turing machine is a way to store and read memory, and move the tape (instruction pointer) if I remember right. If that’s correct, you can come up with an infinitely complex machine with 3 instructions (provided you have an infinite amount of tape).
- n2d4 3y ago
  TypeScript's specification is very out-of-date. The best "specification" for the language is "whatever the compiler does." (It's a double-edged sword because it lets the TypeScript compiler move much faster than any other I've seen, but the lack of standardization regularly causes unintended breaking changes, and developing a competing-but-compatible type checker is basically impossible.)
deleted 3y ago
[deleted]

jonahx 3y ago

I believe in both cases the Turing completeness is accidental, and in the case of CSS a security concern. (In the case of TS, see https://github.com/microsoft/TypeScript/issues/14833 https://github.com/microsoft/TypeScript/issues/14833) If anyone has more historical evidence that this is so for CSS, reactions from original authors, etc, or further evidence in the case of TS, I'd be curious to see it.

Dylan16807 3y ago
Security concern how? Also CSS can't iterate so it's just at the level of arithmetic.

Kinrany 3y ago

Any sufficiently advanced type system necessarily becomes Turing complete because type systems generalize to full compile time programming

IshKebab 3y ago

There isn't really any advantage of artificially limiting the power of type systems. Yes you shouldn't implement Flappy Bird in a type system... but just don't do that. This is obviously for fun.

jlfsdlkj 3y ago

If you ever wrote any JS pre-typescript and then switched to typescript, I do not think you would call the problem "very limited niche."

nicoburns 3y ago

If you think about it, then it makes quite a lot of sense that a type system aiming to describe the behaviour of a dynamically typed language would end up being this powerful.

taneq 3y ago
Having recently finished I Am A Strange Loop, I'm starting to think it's harder for any formal system to not be Turing-complete than it is for it to be so.

tshaddox 3y ago

For TypeScript I'm not really sure what you would expect them to change just to avoid being Turing complete. Its Turing completeness is a straightforward consequence of its basic building blocks: iteration, conditional types, and recursive type definitions. Of course TypeScript could go out of its way to avoid Turing completeness by just specifying a maximum recursion depth or something similar, but why?

RussianCow 3y ago
> specifying a maximum recursion depth or something similar Doesn't TS do exactly this? It doesn't seem like setting a cap on recursion depth would disqualify something from being Turing complete. Or am I misunderstanding your comment?
- explaininjs 3y ago
  When recursion is the only method of iteration, of course it would.
  - smacke 3y ago
    Is the recursion limit an implementation detail of the compiler though, or something statically built into the language? If the former there's nothing to prevent the language itself from being Turing complete. (Similar to how every Turing complete programming language today runs on something technically weaker than a Turing machine due to finite memory.)
    - explaininjs 3y ago
      There’s no spec so the compiler is the language.
  - olalonde 3y ago
    What is the other method of iteration? Also, TypeScript does have a recursion limit[0]. [0] https://herringtondarkholme.github.io/2023/04/30/typescript-magic/ https://herringtondarkholme.github.io/2023/04/30/typescript-...

deleted 3y ago

[deleted]

a_wild_dandan 3y ago

Why? What benefits would we maybe gain by weakening TypeScript?

_gabe_ 3y ago

Isn’t every programming language simply a spec? C and C++ are infamous for just being a spec, with lots of undefined portions resulting in undefined behavior. And if every programming language is a spec, should we inhibit the flexibility of what you can do in them? (I think the answer here is no, but maybe there’s a good reason for limiting what you can do) Edit: Additionally, it takes very little to define a specification that leads to emergent behavior. That’s not necessarily a bad thing. It’s been awhile, but all you need for a turing machine is a way to store and read memory, and move the tape (instruction pointer) if I remember right. If that’s correct, you can come up with an infinitely complex machine with 3 instructions (provided you have an infinite amount of tape).

n2d4 3y ago
TypeScript's specification is very out-of-date. The best "specification" for the language is "whatever the compiler does." (It's a double-edged sword because it lets the TypeScript compiler move much faster than any other I've seen, but the lack of standardization regularly causes unintended breaking changes, and developing a competing-but-compatible type checker is basically impossible.)

deleted 3y ago

[deleted]