17.3. Fixed point

exceptions are not exceptional, they represent expectable problems

In other words, once you've used Maybe you cannot hit nil with a missing method. This is remarkable because even &. doesn't save you from omitting || "No state" at the end of the computation. Basically, that's what they call "Type Safety".

Software architecture is about making fundamental structural choices that are costly to change once implemented.

In the telecommunications industry, on a conceptual level, value-added services add value to the standard service offering, spurring subscribers to use their phone more and allowing the operator to drive up their average revenue per user.

note that TRB source code modifications are not proprietary

Both kill with a job specifier and terminal signals send to the entire process group, so both the shell and sleep.

If any of the inputs are invalid, #execute won't be run.

There are times where it is useful to know whether a value was passed to run or the result of a filter default. In particular, it is useful when nil is an acceptable value.

main > h = {key_with_nil_value: nil}
=> {:key_with_nil_value=>nil}

main > h[:key_with_nil_value]
=> nil

main > h[:missing_key]  # this would be undefined in JavaScript (a useful distinction) rather than null, but in Ruby it's indistinguishable from the case where a nil value was actually explicitly _supplied_ by the caller/user
=> nil

# so we have to check for "missingness" ("undefinedness"?) differently in Ruby

main > h.key?(:key_with_nil_value)
=> true

main > h.key?(:missing_key)
=> false

When you run this interaction, two things will happen. First ActiveInteraction will type check your inputs. Then ActiveModel will validate them. If both of those are happy, it will be executed.

Inside the interaction, we could use #find instead of #find_by_id. That way we wouldn't need the #find_account! helper method in the controller because the error would bubble all the way up. However, you should try to avoid raising errors from interactions. If you do, you'll have to deal with raised exceptions as well as the validity of the outcome.

For this one we'll define a helper method to handle raising the correct errors. We have to do this because calling .run! would raise an ActiveInteraction::InvalidInteractionError instead of an ActiveRecord::RecordNotFound. That means Rails would render a 500 instead of a 404.

Amid awful suffering and deteriorating conditions, Texas Republicans decided to fight a culture war.

That's the whole point of an abstraction layer—to isolate your business logic from a subsystem's mechanics

My understanding of "programming to an interface" is different than what the question or the other answers suggest. Which is not to say that my understanding is correct, or that the things in the other answers aren't good ideas, just that they're not what I think of when I hear that term.

If the program was important enough, Microsoft might actually go ahead and add some hack to their implementation so the the program would continue to work, but the cost of that is increased complexity (with all the ensuing problems) of the Windows code. It also makes life extra-hard for the Wine people, because they try to implement the WinAPI as well, but they can only refer to the documentation for how to do this, which leads to many programs not working as they should because they (accidentally or intentionally) rely on some implementation detail.

Encapsulation is used to hide the values or state of a structured data object inside a class, preventing direct access to them by clients in a way that could expose hidden implementation details or violate state invariance maintained by the methods.

with ActiveForm-Rails, validations is the responsability of the form and not of the models. There is no need to synchronize errors from the form to the models and vice versa.

DSLs can be problematic for the user since the user has to manage state (e.g. am I supposed to call valid? first or update_attributes?). This is exactly why the #validate is the only method to change state in Reform.

we get the benefit of isolating request specific logic without cramming it into a ActiveRecord model that will be used in multiple controllers/actions

The press will tell you that "the concept" is great but the execution is bad. What should I tell you? The experience is shallow. The game is mediocre. But listen carefully, when a game is mediocre and can't even make you feel something then it's the worst kind of gaming. I will give it a 4 out of 10. You know, if this was a test in a school then this game should be marked D (someone answered a few questions, but overall missed the point). I understand that many people care about the "concept" of this game, but why if the experience is just... not here. I'm talking about the experience becaus We. The Revolution tried to be an actual experience. And it fails so badly.

the gameplay is meaningless and the devs just missed the point.

Unlike naming children, coding involves naming things on a daily basis. When you write code, naming things isn’t just hard, it’s a relentless demand for creativity. Fortunately, programmers are creative people.

If we renamed things more often, then it probably wouldn’t be so hard to name them in the first place.

This is funny because it’s unexpected. Cache invalidation sounds like a hard thing, while naming sounds more straightforward. The joke works because it violates our expectation that hard things should be technical. It’s also funny because it’s true.

So the hard and unsolvable problem becomes: how up-to-date do you really need to be?

After considering the value we place, and the tradeoffs we make, when it comes to knowing anything of significance, I think it becomes much easier to understand why cache invalidation is one of the hard problems in computer science

Now let me ask you, do you write JS for a single page application differently from a "traditional" web application? I sure hope you do! In a "traditional" application, you can get away with being sloppy because every time the user navigates to a new page, their browser destroys the DOM and the JavaScript context. SPAs, though, require a more thoughtful approach.

Technically, it isn’t a part of the comparison internally but it is a factor that some users care for.

When people talk about "beginner distros" they mean distros that are no hassle to get started, it doesnt mean they are somewhat inferior or less capable.

The key phrase here is “children of a grid container.” The specification defines the creation of a grid on the parent element, which child items can be positioned into. It doesn’t define any styling of that grid, not even going as far as to implement something like the column-rule property we have in Multi-column Layout. We style the child items, and not the grid itself, which leaves us needing to have an element of some sort to apply that style to.

Flexbox: content dictates layout

And if there's a suitable vulnerability, it might be possible to trigger it even without using <iframe>, <img> or <a> element, so it's not worth considering for this issue.

We can certainly explain the issues snap cause without using political or religious arguments. We did so in the documentation I linked to above.

Blocks Don’t Need 100% Width When we understand the difference between block-level elements and inline elements, we’ll know that a block element (such as a <div>, <p>, or <ul>, to name a few) will, by default expand to fit the width of its containing, or parent, element (minus any margins it has or padding its parent has).

It’s easy to think of 1fr as being “one part of the space in the grid container” when it is really one part of the space left over.

Making literal grids. Like X columns with Y gap between them homegrown framework stuff. grid-gap is wonderful, as gutters are the main pain point of grid systems.

No, this is not a duplicate of that linked question. I don't need to know "why it's a snap". I want to know how to use it without snap.

I think you’re missing the spirit behind the classic “centering is hard” complaint in a couple of places, which, at least for me, always comes back to not knowing the height of the elements.

The alternative is uncontrolled components, where form data is handled by the DOM itself.

This is a dynamic value because of hybrid devices which can use a mix of mouse and touch input.

if you set text-decoration: underline for all links then you will have to set text-decoration: none for special links which you don't need an underline.

From morn to night

Doubt is fled=stuck to their opinions

delight=bliss in not understanding?

opening morn=sunrise

truth new born

It’s all very well telling Canonical what to do, but someone needs to pay those developers for their time. It’s not free.

Repeatedly posting in this thread that there are problems, won’t actually get anything fixed.

The best place to let the developers know, and track those bugs is in the bug tracker. There are hundreds of forums online, all over the place in many languages. We can’t be expected to read all of them. Anyone with a launchpad ID (thus, anyone who has an account on this discourse instance) has the capability to file a bug. I’d strongly recommend doing so, for each specific issue. Taking just a few minutes to do that will help tremendously.

Just saying “snaps are slow” is not helpful to anyone. Because frankly, they’re not. Some might be, but others aren’t. Using blanket statements which are wildly inaccurate will not help your argument. Bring data to the discussion, not hearsay or hyperbole.

Progress is made of compromises, this implies that we have to consider not only disadvantages, but also the advantages. Advantages do very clearly outweigh disadvantages. This doesn’t mean it perfect, or that work shouldn’t continue to minimize and reduce the disadvantages, but just considering disadvantages is not the correct way.

Only folks who help package Chromium get to decide how Chromium gets packaged. This gives anyone two options: You can get involved and help package Chromium so you have a voice in the decision-making, or not.

We can lay blame for this semantic drift squarely at the feet of trend. Designers and developers eager to try the latest and greatest invite ambiguity in with outstretched arms. Leadership chases perceived value to stay relevant.

However, the W3C provides us with an important clue as to who is right: the download attribute.

The debate about whether a button or link should be used to download a file is a bit silly, as the whole purpose of a link has always been to download content. HTML is a file, and like all other files, it needs to be retrieved from a server and downloaded before it can be presented to a user. The difference between a Photoshop file, HTML, and other understood media files, is that a browser automatically displays the latter two. If one were to link to a Photoshop .psd file, the browser would initiate a document change to render the file, likely be all like, “lol wut?” and then just initiate the OS download prompt. The confusion seems to come from developers getting super literal with the “links go places, buttons perform actions.” Yes, that is true, but links don’t actually go anywhere. They retrieve information and download it. Buttons perform actions, but they don’t inherently “get” documents. While they can be used to get data, it’s often to change state of a current document, not to retrieve and render a new one. They can get data, in regards to the functionality of forms, but it continues to be within the context of updating a web document, not downloading an individual file. Long story short, the download attribute is unique to anchor links for a reason. download augments the inherent functionality of the link retrieving data. It side steps the attempt to render the file in the browser and instead says, “You know what? I’m just going to save this for later…”

It’s worth mentioning that Svelte limits its scope to being only a UI component framework. Like React, it provides the view layer, but it has more batteries included with its component-scoped CSS and extensible stores for state management. Others like Angular and Vue provide a more all-in-one solution with official routers, opinionated state management, CLIs, and more. Sapper is Svelte’s official app framework that adds routing, server-side rendering, code splitting, and some other essential app features, but it has no opinions about state management and beyond. Some devs prefer Svelte’s minimal approach that defers problems to userland, encouraging more innovation, choice, and fragmentation, and other devs prefer a more fully integrated toolkit with a well-supported happy path.

What pain point are you perceiving?

Trying to find a new day job is full-time work

There's a huge area of seemingly obvious user-centric products that don't exist simply because there isn't a working business model to support it.

No program is an island. Every program has to hook into the operating system at some point, if nothing else.

delete will only work on properties whose descriptor marks them as configurable.

Svelte by itself is great, but doing a complete PWA (with service workers, etc) that runs and scales on multiple devices with high quality app-like UI controls quickly gets complex. Flutter just provides much better tooling for that out of the box IMO. You are not molding a website into an app, you are just building an app. If I was building a relatively simple web app that is only meant to run on the web, then I might still prefer Svelte in some cases.

That’s how developers create buttons — they add padding to their div containers, not heights.

from my point of view, it is (by far) the best way, to build a layer on top https://github.com/material-components/material-components-web . This is also the path that the Angular Material team has taken, although they have already made a huge effort to create the components themselves.

is not required to point to "svelte": "src/main.html" if you're bundling for es, "module": "dist/main.mjs" would suffice. I mean, it's a good thing to provide a single file, not the whole sources again.

this in particular comes from the addressee

origin

Man, for some reason, I really like this answer. I recognize it's a bit more complicated, but it seems so useful. And given that I'm no bash expert, it leads me to believe that my logic is faulty, and there's something wrong with this methodology, otherwise, I feel others would have given it more praise. So, what's the problem with this function? Is there anything I should be looking out for here?

Assignments to $-prefixed variables require that the variable be a writable store, and will result in a call to the store's .set method.

const useEffect = (subscribe) => ({ subscribe })

I wondered about that. But as you mention, the control flow makes it tricky, because it's not really a template literal — it's a DSL. I thought perhaps it's better to have something that's explicitly different, than something a bit 'uncanny valley'.

The following examples are minimal, clean starting points using compose file version 2. Again they are not intended as a definitive reference.

There are contradicting definitions: "dependence: one that is relied on", "dependency: something that is dependent on something else", "dependent: one that is dependent" which also says "archaic : DEPENDENCY" which is certainly the inverse of what is usually meant in technology... is it more correct to install the "dependences"? (wiktionary gives it as the plural)

For performance reasons, $: reactive blocks are batched up and run in the next microtask. This is the expected behavior. This is one of the things that we should talk about when we figure out how and where we want to have a section in the docs that goes into more details about reactivity. If you want something that updates synchronously and depends on another value, you can use a derived store:

I'm afraid there's only so much the docs & tutorials can do about something like this actually. When you first read them, you don't get Svelte well enough (since you're reading a tutorial...) for this to make sense to you. Then you try something, encounter a behaviour, question it, understand better... That's learning.

The index.js file is the main entry point and imports and exports everything from internal.js that you want to expose to the outside world.

The internal.js module both imports and exports everything from every local module in the project

Every other module in the project only imports from the internal.js file, and never directly from other files in the project.

The crux of this pattern is to introduce an index.js and internal.js file.

as soon as you have a (indirect) circular dependency, you might be interacting with a half loaded module in your code.

Could you please explain why it is a vulnerability for an attacker to know the user names on a system? Currently External Identity Providers are wildly popular, meaning that user names are personal emails.My amazon account is my email address, my Azure account is my email address and both sites manage highly valuable information that could take a whole company out of business... and yet, they show no concern on hiding user names...

One of Svelte's advantages, for me, is that I can test out ideas with relatively few lines of code. the #with feature could save me from adding a separate component for the content of an #each loop. I get frustrated when I have to create a new file, move the content of the #each clause, import it as a component, and add attributes and create exports for that, and implement events to send messages back, and event handlers, when I just wanted to test a small feature.

Wondering how to get field state from multiple fields at once? People coming from Redux-Form might be wondering where the equivalent of Redux Form's Fields component is, as a way to get state from several fields at once. The answer is that it's not included in the library because it's so easy to write one recursively composing Field components together.

Also, if you don't put that implementation of URLSearchParams in the global scope you're not using it as a polyfill but a ponyfill, and those are meant for your code, not for external dependencies.

JavaScript is, of course, a dynamic language that allows you to add and remove objects and their members at any point in time. For many, this is precisely why they enjoy the language: there are very few constraints imposed by the language.

Just like elements can have children... <div> <p>I'm a child of the div</p> </div>...so can components. Before a component can accept children, though, it needs to know where to put them. We do this with the <slot> element.

mixing the turing complete of javascript with the markup of HTML eliminates the readability of JSX so that it is actually harder to parse than a solution like hyperscript

However, this would lead to further divergence. Tooling that is built around the assumptions imposed by template literals wouldn't work. It would undermine the meaning of template literals. It would be necessary to define how JSX behaves within the rest of the ECMAScript grammar within the template literal anyway.

Template literals work well for long embedded DSLs. Unfortunately the syntax noise is substantial when you exit in and out of embedded arbitrary ECMAScript expressions with identifiers in scope.

conveys the significance of emotionally investing in your children when they are young and being a ‘present father’

And as an aside, I’m definitely in favor of more debates than sessions in future conferences, since we actually learn more by hearing multiple viewpoints.

About the argument against it, "{@const will make code less consistent ": I think the same is true now, since people can come up with very different ways of dealing with the "computed value inside each loop/if function" problem. Some extract components, some use functions, some will prepare the array differently beforehand.

but this RFC addresses a significant pain point I've had with {#each} blocks doing data visualization and graphics.

This is exactly why I'm in favor of @const. Helpers are fine, except when they're not and turn into boilerplate.

Right, because those are the only 3 instances where new "scopes" are created, which means you're seeing data for (probably) the first time.

I like this, mostly because it allows me to write small components without creating another separate sub-component for holding the value simple computation. I get annoyed every time I need to create a component just to hold a variable, or even move the computation away from the relevant location. It reminds me of the days where variables in C had to be declared at the top of the function.

The clean-up function runs before the component is removed from the UI to prevent memory leaks. Additionally, if a component renders multiple times (as they typically do), the previous effect is cleaned up before executing the next effect. In our example, this means a new subscription is created on every update.

The readable store takes a function as a second argument which has its own internal set method, allowing us to wrap any api, like Xstate or Redux that has its own built in sub­scrip­tion model but with a slightly different api.

Putting a browserlist in the project will send a false signal to users. Svelte is only a lib, not an application. The consumer / implementer will have to decide what level of support he wants, according to its constraints/userbase and adjust its build process and polyfills implementation.

A lot of instructions I read say things like npm install niftycommand and then niftycommand. But this will never work unless you have ./node_modules/.bin in your path, will it?

Auto-subscription only works with store variables that are declared (or imported) at the top-level scope of a component.

Why do I need a global variable? Is the global requirement from ES6 modules (I'd have thought modules would be in a functional scope) or rollup?

Rollup will only resolve relative module IDs by default.

DX: start sapper project; configure eslint; eslint say that svelt should be dep; update package.json; build fails with crypt error; try to figure what the hell; google it; come here (if you have luck); revert package.json; add ignore error to eslint; Maybe we should offer better solution for this.

When the message say function was called outside component initialization first will look at my code and last at my configuration.

If calling query() results in calls to Svelte's context API, then it needs to be called synchronously during component initialization.

Most simple example: <script> import ChildComponent from './Child.svelte'; </script> <style> .class-to-add { background-color: tomato; } </style> <ChildComponent class="class-to-add" /> ...compiles to CSS without the class-to-add declaration, as svelte currently does not recognize the class name as being used. I'd expect class-to-add is bundled with all nested style declarations class-to-add is passed to ChildComponent as class-to-add svelte-HASH This looks like a bug / missing feature to me.

We should also allow passing unrecognised props to the rendered component. eg: tabindex might be required on some instances of a component, and not all. Why should developers have to add tabindex support to their components just that it may potentially be used

The language should work for developers, not the other way around.

feel like there needs to be an easy way to style sub-components without their cooperation

The problem with working around the current limitations of Svelte style (:global, svelte:head, external styles or various wild card selectors) is that the API is uglier, bigger, harder to explain AND it loses one of the best features of Svelte IMO - contextual style encapsulation. I can understand that CSS classes are a bit uncontrollable, but this type of blocking will just push developers to work around it and create worse solutions.

I'm just pushing on the "is this really a good idea" front

This property makes the element so that it no longer seems to exist.

But this is a case where it feels like we're papering over a deficiency in our language, and is the sort of thing detractors might well point to and say 'ha! see?'.

Yes, they do but none of them allow arbitrary javascript anywhere in the template it is finely controlled. This deviates from that, in fact that is it's defining feature.

Adding my 2 cents to the discussion. Adding a class prop to a component doesn't necessarily mean it should apply the style to the root element, but it makes sense that it should apply it the main element visually. Let's take a modal component as an example.

You're not trying to pass a class to a dom element. You're passing a class to a component. It's up to the component to define what that means for the components use case. In most cases it would be passed to a dom element.

Reactive statements run immediately before the component updates, whenever the values that they depend on have changed.