One of my favorite programming sayings is "I've learned there are worse things than boilerplate."

Over the years I've found that most things promising to "reduce boilerplate" do so in ways that make maintenance and debugging harder. I think back with regret on the times I decided to accept that tradeoff, and I think this falls under that category. I wouldn't recommend it. :)

I haven't tried it, but I love the idea!

I think Elm doesn't have a concrete roadmap because Evan adapts his plans based on what he learns from the community. If you ask him "what will you be working on 6 months from now?" the answer will probably be "depends on what happens in the next 6 months." He does post periodic status updates on the elm-dev mailing list, if you're wondering what he's working on and how it's going.

My understanding is that the Elm Software Foundation is primarily for organizing money-related things. The main reason it exists is that Evan is friends with Python creator Guido van Rossum, and Guido recommended that he set up a nonprofit a la Python Software Foundation. It's not really for project management or anything like that.

He only works on Elm. He's worked here for over a year and he's never touched our product repo. :)

Favorite part (I'm gonna go with the American spelling, sorry!) is the feeling of invincibility when refactoring. I get some exciting idea for how to make my code cleaner, and I just do it. I don't worry about regressions, and lo and behold, when it all compiles again it still works! That feeling never seems to get old.

Worst part? Being smack dab in the middle of two communities that are almost polar opposites. Many people coming to Elm from JavaScript want Elm to be more like JavaScript, and many people coming from Haskell want Elm to be more like Haskell. I see Elm as its own thing—neither "JavaScript enhanced" nor "Haskell simplified"—and I've sometimes struggled to engage constructively with groups who don't see it the same way.

Where do you see the future of Elm?

Someday I see it being an awesome back-end language too, but that's quite a ways off I think. With respect to the browser, I see the future of Elm being one where Elm's ecosystem becomes one of its biggest selling points.

Right now Elm's ecosystem is much smaller than JavaScript's, so ecosystem is a drawback overall. However, the overall quality of the Elm ecosystem is much higher - in terms of usability and reliability - than the (much larger!) JS ecosystem. I think this quality-over-size trend is likely to continue, because Elm's package manager has a blanket policy of accepting only Elm code, not JavaScript code.

As the gaps in the ecosystem fill in over time, I see the high-quality Elm ecosystem becoming a big selling point. Today people say "Elm's ecosystem is so small, you inevitably have to do some JS interop" but I think in the future people will say "Elm's ecosystem is big enough to meet all the needs of a typical web app, and it is so much nicer than the JS ecosystem."
We're not there yet, but we're headed in that direction. It will take time, but I think it'll absolutely be worth it. :)

Can you envision Elm becoming more mainstream?

Definitely. For any language aimed at industry use, I think success stories among industry early adopters are likely to predict long-term adoption. A very high percentage of Elm's early adopter stories are on the extreme end of positive.

I think the direction JS is moving is helping Elm out a lot. Virtual DOM libraries, type-checking, and functional programming concepts are all becoming more mainstream in JS, each of which narrows the familiarity gap between what people are using on JS teams and what they could be using if they introduced Elm.

How do you feel the community can help make this happen?

Posting experience reports. These are the biggest ways to help things become more mainstream, because people look for data points when making decisions about whether to dive into a language.

"I am thinking about trying Elm. Who else has done that? How did it go? Would the benefits help our team too? Did the costs seem like costs we can accept?" The more data points out there, the more easily people can make informed decisions about these things.

Our story at NoRedInk is out there, but do people know your story? If not, help them out by writing about it!

Sure! I should emphasize that we don't put a big priority on "getting this right." More than anything we try to be consistent (but don't always succeed), and the compiler makes it pretty easy to rename things if we change our minds, so we don't sweat it. (The biggest drawback to renaming is plain old vanilla merge conflicts.) So I wouldn't take any of this as advice so much as a data point if you're curious. :)

We have a series of pages, e.g. "Teacher Dashboard", "Grading", "Splash Page". Each of these has its own main; back when I joined the company we were a non-SPA Rails app, and we have not transitioned to SPA yet. (We have long-term plans to head in that direction, and I don't expect the transition to affect our module structure much - outside of main, of course, but main modules are a small fraction of our total modules.)

We have a top-level module namespace called Nri for things specific to our UI, as opposed to things that we might open-source someday (e.g. the Analytics module, the Emoji module, etc). Here's an example of three related ones:

Nri.QuizHeader.Model
Nri.QuizHeader.Styles
Nri.QuizHeader.View

So our Quiz Header has a model, and a view, and some elm-css styles. (We've been migrating from Sass to elm-css and it's been sweet!) We don't have a Nri.QuizHeader.Update because the quiz header doesn't have any state. I think this is worth emphasizing, because I see people create a model/update/view any time they want to reuse code, and I think that's the wrong way to scale. Unnecessary state management is bloat! We had no need for an update function here, so it was simpler not to have one.

Plenty of times we just have a module to hold view, and plenty of others it's not even a separate module, it's just a plain old function inside an existing module, e.g. viewSidebar : User -> Html msg

We also have reusable views that are used across multiple pages, for example:

Nri.Tabs
Nri.TextInput
Nri.Toggleable
Nri.Tooltip

All of these are stateful, and their APIs looks like github.com/evancz/elm-sortable-table - they do not define their own Msg types, and callers don't have to use Cmd.map. Their states are super simple, and defining their own Msg types would have been overkill - more trouble than it was worth. This is also worth emphasizing; immediately reaching for a custom Msg and Cmd.map any time local state is involved is a surefire way to get needlessly overcomplicated wiring.

My rule of thumb is that reusable views where view returns Html msg instead of Html Msg are nicer by default, and I only reach for a custom Msg once I have enough state transitions that Cmd.map would reduce verbosity substantially.

Finally we have some reusable data structures, which begin with Data., for example:

Data.Assignment
Data.Assignment.Decoder

We debated the right namespace for these and settled on Data because what they have in common is that they're about representing and encoding/decoding some piece of data.

These are a mix of various union types and type aliases that represent common data structures in our app. Some of them have a lot going on, so it's decently common to have a data structure defined in one module, and then the decoder and/or encoder in a separate module. It's no big deal if they live in the same module, though. Again, we don't spend a ton of time on module structure because it's so easy to change reliably if we change our minds.

Hope that helps!

I got into React very early after Facebook open-sourced it, but I switched to Elm before Redux came out...so I've never actually used Redux. :)

I think the following is the most honest way for me to answer the question of pros + cons:

The Elm Architecture in Elm

It's the only game in town. If you want to build UIs in Elm, the Elm Architecture is the only way to do so.

Pros: the entire ecosystem is optimized around it; no fragmentation
Cons: it's not well suited to doing major manual DOM manipulation

The Elm Architecture in JS

I've never tried this. JS is a totally different language, and I don't think it would be useful for me to guess what it might theoretically feel like to use Elm Architecture in JS. A better person to ask would be someone who's tried precisely this, and especially someone who's also tried Redux. :)

If the subtext here is "can I get many of Elm's benefits by using the Elm Architecture in JS?" the answer is unfortunately "not even remotely close." In my opinion almost all of Elm's benefits come from its compiler and library ecosystem, and you can't access either from JS.

This was the subject of my ReactiveConf 2016 talk, so I'll defer to that! :)

We actually started with some business logic in our quiz engine. I wrote a guide for how to do this, but I haven't updated it since Elm 0.16. (This reminds me that I should really get around to that...) I forget where we first used Elm for actual rendering, but it started to snowball pretty quickly after that.

The biggest roadblocks were around build tooling. I didn't do a good job figuring out how production deployments (via Rails - we hadn't started using Webpack at that point) would differ from development builds, and the build tool plugin ecosystem wasn't as far along as it is today. (And it's still got a ways to go.) I guess maybe "roadblock" is too harsh, since we got past it, but even after migrating a bunch of stuff to Webpack we're still dissatisfied with our build process overall—and not just with the Elm parts.

I like Evan's preferred term: "Elm programmers"

I heard a great point once, which is that calling ourselves "Elmists" or "Elmers" or "Elmos" kind of suggests that we're a tribe, that we treat the language as more than a tool we use for a particular job.

But at the end of the day, that's what it is: a tool we use for a particular job! We should choose Elm when we think it's a good fit, and choose other tools when they're a better fit - not because we're part of a tribe. :)

As the ops guy at NRI responsible for Elm, the main source of errors with Elm is actually during builds. From 0.15-0.17, Elm did not correctly handle the caching of artifacts, leading to occasional compile errors that were not reproducable easily. It was simple enough to fix - just wipe the artifacts. But that also slowed the builds down a lot.

I'm also fairly certain I'm the leading expert on runtime exceptions in Elm - it's possible to make them happen, but most of the time you have to really understand Elm to make them happen. Unless you're using Array or Regex, of course. Both of these can lead to runtime exceptions - e.g Regex.regex "[a". However, you'll not likely run into that in production - unless you are taking using input as regex input.. which probably isn't a good idea unless you're escaping things.

That seems overcomplicated, yeah. I wouldn't do that. :)

I like Atom because its Elm plugin support is fantastic, and its Vim plugin support is among the best you can get outside Vim itself.

In particular the Elm-related plugins I use with Atom are:

• linter-elm-make
• language-elm
• elm-format
• elmjutsu

Not on purpose. Wouldn't be surprised if a Debug.log slipped through at some point though. 😅

Evan has already done a chunk of work on it. I don't know exactly when it'll be out, but I'd be surprised if it weren't sometime in 2017.

In the meantime, take a look at github.com/eeue56/elm-server-side-...

EDIT: here ya go!

dev.to/rtfeldman/tour-of-an-open-s...

...Previously I had said this:

People ask this a lot, and unfortunately I still don't have a go-to project I can point to.

Right now it kind of feels like "serious Elm project" / "used in production" / "open source", pick two.

Laphroaig Lore!

laphroaig.com/lore

I'd say the main way it's impacted my Elm coding is prioritization on my side projects.

Specifically, I'm like "ooh, it would be so awesome if ______ feature of elm-test were shipped before I get to the Testing chapter, so I can write about it!" That's happened with elm-test more than any other project, and I'm really pumped about its next release. :D

I tend to pull things into the toplevel early and often, but I also tend to use the (|>) operator wherever possible.

That said, I wouldn't call having several declarations in the same let a bad thing per se. So long as you find it readable, it's unlikely to cause problems outside that let, so I wouldn't worry about it. :)

I actually have no idea. I know the ones at the bottom of elm-lang.org do, but I keep hearing about new ones and being like "wait, you do?" and then forgetting their names. 😅

I really don't want to give this answer, but: no, I can't.

The key there is JS framework. There are things that JavaScript makes easier than Elm (e.g. when we want manual DOM manipulation instead of going through a Virtual DOM system), but in those cases we just use JS interop - getting a JS framework involved would be way overkill for those use cases.

And for everything else, a JS framework would just be a huge downgrade. I can't think of a single thing we've built where a JS framework would be a better experience. Any of them.

I recently became Director of Engineering, so now it's a lot more meetings than it was a month ago! (That does give me a broader perspective on our team, though, which is cool.) Prior to that I was doing a lot of pair programming; we encourage it, and I ❤️ the people I work with! There's also the usual mix of non-programming stuff - reviewing each others' pull requests, interviewing, etc.

One of the things I've been working on lately is pair programming to help port some of our old React code (which I wrote back in the day) to Elm, since I'm a silo on a lot of the domain knowledge on our pre-Elm UI code.

Evan would lose a valuable feedback loop, but the language would be fine. Suffice it to say, he's thought about this, and has plans for how he could keep focusing on Elm even without a patron employer like NoRedInk (or Prezi before us).

Yeah, for API keys I recommend creating something like Secrets.elm and adding that file to .gitignore. Locally, developers have to create that file as part of setting up their systems, and then you have your build process swap in a different file (containing different constants) for production builds.

This way you can easily access the secrets from any module, and if you forget to set them up locally, you'll get a compile error because the module won't be found!

I do this with the Frontend Masters workshop for GitHub API access tokens; you can check out the repo here github.com/rtfeldman/elm-workshop

What are the next big things in store for Elm that you're excited about?

Asset management - what Evan's working on right now - as well as the next release of elm-test, and the improvements to the debugger Yosuke Torii has been working on.

There are also lots of smaller things I'm excited about, like union types becoming comparable, which is vaguely in the pipeline somewhere, and broader coverage of the Web platform. So much awesome in the works! 😸

What's it like writing Elm in Action?

Time-consuming! It's swallowed just shy of my entire social life.

It's also one of the most rewarding projects I've ever worked on, so no regrets in committing to it. :)

What is the best way to start contributing to Elm (ex. Good starting places?)

Evan curates a list of projects at github.com/elm-lang/projects - but I'd also like to put in a shameless plug for elm-css - the CSS spec is huge, and there are lots of ways to improve our coverage of it!

Yep! My current plans for 2017:

• QCon London in March
• Devoxx San Jose in March
• GOTO Chicago in May
• Elm Europe in June
• elm-conf in September
• ReactiveConf in October

There totally is! github.com/elm-lang/projects

About 25% of our users are on tablets, so we always have to keep touch in mind. When possible we've used pointer events (with polyfill) to keep things consistent, but that hasn't always been realistic for some drag-and-drop stuff. We haven't used any touch-related subscriptions yet.

It's still WIP, but you can see some non-polyfilled touch stuff we're doing in github.com/NoRedInk/drag-and-drop - which is already open source, but very unpolished at this point. For example, there's still more JS interop in there than there needs to be. 😄

I totally get the frustration, but basically I think this is the least bad option. We've tried various ways to accelerate this, and all the cures have ended up being worse than the symptoms.

That said, Evan moves much faster than TC39, so catching up seems more or less inevitable—just not as quickly as we'd all like. :)

February 25, 2018, at 7:42am UTC! ;)

The pain point that leaps immediately into my mind is build tools. I'm not gonna sugarcoat it: Webpack has been slow and crashy and I can't wait for us to stop using it.

However, I'm assuming you meant "pain point specifically with Elm the language." For me it's definitely that union types are not comparable yet. I really want to be able to use them as keys in a Dict for things like form validation. Unfortunately this is a ways off because the implementation requires modifying how Elm generates JS code to include a bit more information at runtime.

My #2 pain point is how much of the Web platform still requires interop to access. For example, if I could use an Elm library with a nice API that let me work with IndexedDB, I'd probably be up until 2am upgrading Dreamwriter.

Oh, and there's that value doesn't Just Work the way it does in React. This is kind of inside baseball, but it can Just Work in React because setState updates synchronously, whereas Elm does requestAnimationFrame batching to improve performance. The alternative of defaultValue works fine for most use cases, but when it doesn't it's a big pain. I can conceive of a way to make value Just Work, but it would be a pretty invasive change for elm-lang/virtual-dom.

Elixir is super new for us, so the back-end is still almost exclusively Ruby.

We have one Elixir service in production right now, and it's not user-facing. We are currently working on our first (small) user-facing Elixir service, and once that's done, we plan to start working on a third (much larger and more mission-critical) user-facing Elixir service. A ballpark timeline for that third one would be getting it into production six months from now.

Our approach is generally to use new technology when we expect a specific benefit, not just because it's enjoyable. (Although it is certainly enjoyable!) So to the extent that we keep finding ways that doing more Elixir will benefit our code base, we'll keep doing more of it, but we're not going out of our way to rewrite Ruby code in Elixir without a tangible benefit in mind.

We haven't run into performance problems around this, but thank you for surfacing it! There was some discussion around whether this was needed, and the consensus was "in theory it would be useful, but in practice, who knows if it's actually necessary?"

Seems like you've found a case where it is! I'd post specifics of your use case on github.com/elm-lang/virtual-dom/is... - ideally with a link to the D3 code in question.

We actually don't do any kind of A/B testing, so definitely no. ;)

The first chapter of Elm in Action is a free download, and I go into this question there.

Hope it helps!

It's an unorthodox choice for a metalhead, but I'm gonna go with Brian May's solo near the end of Bohemian Rhapsody. I can't not air guitar to that.

I think it's an underrated solo for the usual reason Brian May's stuff is underrated (Freddie Mercury's singing), but that's no fault of his. That solo ROCKS. 🤘

Thank you! So nice of you to say! ❤️

Pretty sure I saw someone (and I think it was you, but I could be misremembering) write Elm code to control a synthesizer!

There is definitely no solid plans for that. WebAssembly gets brought up and that might be a good idea one day but right now it's definitely not.

What Noah said. 😄

At NRI, this isn't really a concern or issue. We don't use Closure compiler, and we currently don't need to. There's a bunch of posts on the mailing list about this though -> groups.google.com/forum/#!searchin... and groups.google.com/forum/#!searchin...

Yeah, I don't have any personal experience comparing them. Sorry!

See dev.to/rtfeldman/i-am-the-author-o... regarding SSR in Elm.

My thoughts on SSR in general are "don't do extra work unless it's going to solve a problem you have." 😄

What is the most difficult part about switching 100% to Elm?

Legacy code - there's rarely a good justification to porting really old code that doesn't get used anymore. (So we haven't really done it!)

Have you thought about going back to JS at some point (at least for an specific project)? I mean, maybe something was really complex/troublesome to build in Elm instead of Js?

Only for Node stuff, as Elm is only built for browsers right now.

For browsers, it's the opposite: I don't think I can ever go back. I can't predict the future or anything, but right now I have a really hard time seeing myself applying for a JS job ever again.

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