Our great sponsors
-
-
cofx
A node and javascript library that helps developers describe side-effects as data in a declarative, flexible API.
-
SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
-
-
-
posterus
Composable async primitives with cancelation, control over scheduling, and coroutines. Superior replacement for JS Promises.
-
-
InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
Agree that try/catch is verbose and not terribly ergonomic, but my solution has been to treat errors as values rather than exceptions, by default. It's much less painful to achieve this if you use a library with an implementation of a Result type, which I admin is a bit of a painful workaround, but worth it. I've recently been using: https://github.com/swan-io/boxed.
By far the greatest benefit is being able to sanely implement a type-safe API. To me, it is utter madness throwing custom extensions of the Error class arbitrarily deep in the call-stack, and then having a catch handler somewhere up the top hoping that each error case is matched and correctly translated to the intended http response (at least this seems to be a common alternative).
I was really hoping this article would discuss the benefits of using raw generators over async/await.
By using async/await, we are inherently limited by the flow control because we are forced into await resolving promises.
This is why libraries like redux-saga[0] or cofx[1] use generators.
https://redux-saga.js.org
Async/await is certainly not promises. In fact it would be much better implemented without promises as I proposed here: https://es.discourse.group/t/callback-based-simplified-async...
I would even say that async/await is anti-promise, it takes the main functionality of promises, a caching layer for results and errors that allows you to add the code continuation later and elsewhere (which is a major footgun imo) and coerces the execution flow back to going on the next line and provided immediately at compile time which results in a cleaner flow but not as clean, stateless, efficient or functional as if you were to remove the promises completely. Having an additional caching layer and state machine around every asynchronous function call is quite inefficient.
The essence of async/await is not promises, it's the underlying javascript generator (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...) functionality combined with asynchronous code to stop and start the generator. It's the ability to pause and resume function execution based on asynchronous operations.
The promise functionality, the caching layer and state machine for results is basically sanitized away with async/await, it becomes dead-weight computation. The only benefit of promises in async/await code is being able to more easily interface with other promise laden code which you don't need once you have async/await and a library like https://www.npmjs.com/package/async for more complex cases.
Note that promises based async/await is also a mess of an implementation that breaks stack traces and needs to support tons of odd statement corner cases (basically anything that can return an object that could be a promise) whereas a continuation passing style async/await would be a much simpler implementation that would only apply to function calls and maintain stack traces. We get that stack trace support automatically because of the great work of whoever implemented javascript generators which seem to already carry stack traces across paused/resumed functions (if you don't wrap in promises).
It drove me crazy too, until I needed to use Puppeteer which requires you to write async/await (there are Puppeteer implementations in other languages, but they all seem to make compromises I didn't want). Generally speaking, async/await allows you to write code that looks and feels serial. Perhaps try using one of the async libraries for PHP to wrap your mind around the concept of async/await (like https://github.com/spatie/async)
Async/Await covers the 80% of use cases for async logic in JS. Most people aren't really using promises as multicast references. They don't call `then` in one place, hang on to the promise reference, then call `then` again somewhere else (perhaps to represent a cached value); they call `then` once on the reference because it's just a moment in a composite operation.
It's for this reason that I think this library[0] is the more appropriate abstraction for that same 80% of use-cases, as its more memory efficient since you can represent the same composite operation that generates multiple promise references with a single object (a unicast reference instead). I haven't learned Rust but apparently the author bases this on Rust's ownership principle.
[0]https://github.com/mitranim/posterus
hyperscript is designed for small, embedded front end scripting needs: toggling classes, listening for events from its sister project, https://htmx.org, etc. It isn't a general purpose programming language for use, for example, on the server side in a node-like environment.
you can still perform things asynchronously by wrapping any expression or command in an `async` prefix:
https://hyperscript.org/commands/async/
but there isn't a mechanism for resolving all of them
although, now, come to think of it, the following would work:
set results to {result1: somethingThatReturnsAPromise(), result2: somethingElseThatReturnsAPromise()}