5 ms·

async/await is just a syntax sugar, most languages didn't have it until very recently when it became a trend or something. In OCAML it's just like any other mon

by nsonha 5y ago

async/await is just a syntax sugar, most languages didn't have it until very recently when it became a trend or something. In OCAML it's just like any other monad you use the bind operator instead. No need for special keywords.

lolive 5y ago
I will probably be banned from any Haskell forum after that, but isn't the do notation a async, and the <- a await ?
- nsonha 5y ago
  what do you mean by banned? You got it the other way around, async is a special case of the do notation, and await is the special case of <-
- Zababa 5y ago
  It's basically that. Example: hello.then(a => return op1(a)).then(b => return op2(b)).then(c => console.log(c); const a = await hello(); const b = await op1(a); const c = await op2(b); console.log(c) In Haskell (>>= is pronounced "bind", \a -> is like a => in JS): hello >>= (\a -> op1 a >>= (\b -> op2 b >>= (\c -> show c))) do { a <- hello; b <- op1 a; c <- op2 b; show c } There is a slight difference, in that JS promises aren't monads. But the idea is still here.
- rsrsrs86 5y ago
  do { a <- m; return r } Ia desugared to m >>= (\a -> return r) Think of it m.then(function (a) return r)
dmitriid 5y ago
> it's just like any other monad Ah yes. The magic word "just". You "just" do something that does something. And yet even the example in the article uses Promise.then and eventual callback hell.
- nsonha 5y ago
  I have to admit I don't know much about ReScript and only have very basic exposure to OCAML, here is how you do await in it: https://github.com/ocsigen/lwt https://github.com/ocsigen/lwt The `let* in` is a generic syntax for monads, it doesn't need a special one just for promise. This was in fact a debate back when async/await was in consideration for ECMAScript, but special syntax is hip so now we have `async/await` for Promise, `.?` for optionals and `flatMap` for arrays, basically the same thing.
  - ackfoobar 5y ago
    Having seen too much `.map(_.map(` in Scala, I'd argue that different words/syntax for different things (that happen to have the same algebraic structure) is a good thing.
    - nsonha 5y ago
      yes but they don't have to be keywords or magical syntax, can be defined in user land
  - dmitriid 5y ago
    > here is how you do await in it That's how you do "await" in a third-party library that brings with it a lot of other baggage. And I doubt it works in ReScript. > The `let* in` is a generic syntax for monads Ah yes. "Just" putting `let*` there magically makes promises work, is that what you're saying? It turns out Lwt gained support for let* sytax only in April 2020. Stupid them. They didn't know they just had to use it.
    - ackfoobar 5y ago
      > It turns out Lwt gained support for let* sytax only in April 2020. I don't understand your point. Monadic let can be done with ppx_let (created in 2016), and even before that there was the older syntax where you write `lwt` instead of `let`. https://github.com/ocsigen/lwt/commit/d28204984646042676570df7ba6b348a635aff58 https://github.com/ocsigen/lwt/commit/d28204984646042676570d...
kevingadd 5y ago
C# 5.0 introduced async/await in mid-2013 (late 2012 depending on how you count it), and F# had it before that in its version 2.0 (~2007). It's a pretty old "trend".
- nsonha 5y ago
  anything else other than those 2? An idea that .Net started, could be good could be bad, but the .Net association isn't added credibility. async/await aren't keywords in F# and kotlin
  - afavour 5y ago
    > anything other than those two? Rust?
    - nsonha 5y ago
      I was arguing that languages are following the "add async/await" trend recently, including rust. That other comment brought up that it exists in C# for a long time, hence not a recent trend.
      - dharmaturtle 5y ago
        https://en.wikipedia.org/wiki/Async/await#History https://en.wikipedia.org/wiki/Async/await#History F# in 2007 C# in 2012 Python in 2015 Typescript in 2015 Javascript in 2017 Rust in 2019 C++ in 2020 Swift in 2021
        sideeffffect 5y ago
        I'm almost sure that Haskell has had its "do notation" even before 2007. And maybe even Scala its "for comprehension".
        dharmaturtle 5y ago
        Yeah - I was limiting my post to explicit async/await. Don Syme, creator of F#, had a nice thread on the roots of async/await, though it doesn't mention do-notation: https://mobile.twitter.com/dsymetweets/status/1407400817917939713 https://mobile.twitter.com/dsymetweets/status/14074008179179... I'm still annoyed that most other languages stole async/await... but not the more general monadic/do notation. Instead we get elvis operators, chaining functions, etc.

by nsonha 5y ago

lolive 5y ago

I will probably be banned from any Haskell forum after that, but isn't the do notation a async, and the <- a await ?

nsonha 5y ago
what do you mean by banned? You got it the other way around, async is a special case of the do notation, and await is the special case of <-
Zababa 5y ago
It's basically that. Example: hello.then(a => return op1(a)).then(b => return op2(b)).then(c => console.log(c); const a = await hello(); const b = await op1(a); const c = await op2(b); console.log(c) In Haskell (>>= is pronounced "bind", \a -> is like a => in JS): hello >>= (\a -> op1 a >>= (\b -> op2 b >>= (\c -> show c))) do { a <- hello; b <- op1 a; c <- op2 b; show c } There is a slight difference, in that JS promises aren't monads. But the idea is still here.
rsrsrs86 5y ago
do { a <- m; return r } Ia desugared to m >>= (\a -> return r) Think of it m.then(function (a) return r)

dmitriid 5y ago

> it's just like any other monad Ah yes. The magic word "just". You "just" do something that does something. And yet even the example in the article uses Promise.then and eventual callback hell.

nsonha 5y ago
I have to admit I don't know much about ReScript and only have very basic exposure to OCAML, here is how you do await in it: https://github.com/ocsigen/lwt https://github.com/ocsigen/lwt The `let* in` is a generic syntax for monads, it doesn't need a special one just for promise. This was in fact a debate back when async/await was in consideration for ECMAScript, but special syntax is hip so now we have `async/await` for Promise, `.?` for optionals and `flatMap` for arrays, basically the same thing.
- ackfoobar 5y ago
  Having seen too much `.map(_.map(` in Scala, I'd argue that different words/syntax for different things (that happen to have the same algebraic structure) is a good thing.
  - nsonha 5y ago
    yes but they don't have to be keywords or magical syntax, can be defined in user land
- dmitriid 5y ago
  > here is how you do await in it That's how you do "await" in a third-party library that brings with it a lot of other baggage. And I doubt it works in ReScript. > The `let* in` is a generic syntax for monads Ah yes. "Just" putting `let*` there magically makes promises work, is that what you're saying? It turns out Lwt gained support for let* sytax only in April 2020. Stupid them. They didn't know they just had to use it.
  - ackfoobar 5y ago
    > It turns out Lwt gained support for let* sytax only in April 2020. I don't understand your point. Monadic let can be done with ppx_let (created in 2016), and even before that there was the older syntax where you write `lwt` instead of `let`. https://github.com/ocsigen/lwt/commit/d28204984646042676570df7ba6b348a635aff58 https://github.com/ocsigen/lwt/commit/d28204984646042676570d...

kevingadd 5y ago

C# 5.0 introduced async/await in mid-2013 (late 2012 depending on how you count it), and F# had it before that in its version 2.0 (~2007). It's a pretty old "trend".

nsonha 5y ago
anything else other than those 2? An idea that .Net started, could be good could be bad, but the .Net association isn't added credibility. async/await aren't keywords in F# and kotlin
- afavour 5y ago
  > anything other than those two? Rust?
  - nsonha 5y ago
    I was arguing that languages are following the "add async/await" trend recently, including rust. That other comment brought up that it exists in C# for a long time, hence not a recent trend.
    - dharmaturtle 5y ago
      https://en.wikipedia.org/wiki/Async/await#History https://en.wikipedia.org/wiki/Async/await#History F# in 2007 C# in 2012 Python in 2015 Typescript in 2015 Javascript in 2017 Rust in 2019 C++ in 2020 Swift in 2021
      - sideeffffect 5y ago
        I'm almost sure that Haskell has had its "do notation" even before 2007. And maybe even Scala its "for comprehension".
        dharmaturtle 5y ago
        Yeah - I was limiting my post to explicit async/await. Don Syme, creator of F#, had a nice thread on the roots of async/await, though it doesn't mention do-notation: https://mobile.twitter.com/dsymetweets/status/1407400817917939713 https://mobile.twitter.com/dsymetweets/status/14074008179179... I'm still annoyed that most other languages stole async/await... but not the more general monadic/do notation. Instead we get elvis operators, chaining functions, etc.