Elm 0.19.1 is a game changer... THANK YOU!

Holy Cow. I am FLOORED.

I just spend the last 7 days upgrading our 46,713 loc Elm app from 0.18 to 0.19.1.

Unbelievable. Amazing. Wow.

It was a bit of work to get rid of the two native functions, etc, etc. But overall very satisfying.

I feel like I just Marie Kondoed the codebase.

At some point, I’ll post a big long thing but just wanted to give a HUGE shoutout to @evancz and whoever else worked on getting it out the door.

It really feels like magic. Like I just tapped into a supercomputer at CERN.

Our Elm codebase is fairly large and, as many functions touch many parts of the codebase, I’d literally take a stroll as my quad-core MacBook Pro pinned all of its CPUs. I’d work with the CPU History floating so I could see from across the room when the build finished. It was typically around 2 to 3 minutes, give or take. It was getting to the point where it was become frustrating to iterate, as I run with the Webpack dev server which compiles on save.

Now, it’s like a second–maybe a 100 to 200x faster? Unreal!

(pause to get actual stats…)

Okay, so here’s changing a “worst-case” module - a 1,500 line file that is used by a ton of modules. It recompiles in under a second! And doesn’t trigger a rebuild of everything under the sun! This used to be a coffee break.

ℹ 「wdm」: Compiling...
Started compiling Elm..
Running elm make /app/assets/elm/src/Main.elm --debug --output /tmp/2019927-24092-3pj1pn.p2vtd.js
Success! Compiled 1 module.

    Main ───> /tmp/2019927-24092-3pj1pn.p2vtd.js

ℹ 「wdm」: Hash: 239d933a426280356c85
Version: webpack 4.41.2
Time: 669ms

The full rebuild after deleting elm-stuff dir:

Running elm make /app/assets/elm/src/Main.elm --debug --output /tmp/2019927-23958-1pp3egr.kz6l.js
Dependencies ready!           
Success! Compiled 100 modules.

    Main ───> /tmp/2019927-23958-1pp3egr.kz6l.js

Hash: aebd6202066d8f290e41
Version: webpack 4.41.2
Time: 3244ms
Built at: 2019-10-27 03:11:12

3.2 seconds for a full build in debug mode?!? Insane! (w/o debug is about 3.0 seconds)

(kinda weird that it’s exactly 100 modules!)

I didn’t really get why the focus on 0.19 was compile speed. Now I do!


Rock on,



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