João Alves (Feb 19 2022 at 14:27): João Alves (Feb 19 2022 at 14:27):Hey how can i start with Roc?
João Alves (Feb 19 2022 at 14:27):Hey
João Alves (Feb 19 2022 at 14:28):How can I be using Roc for first time?
Anton (Feb 19 2022 at 14:39):Hi @João Alves, check out the getting started subsection in the README, link here.
João Alves (Feb 19 2022 at 14:39):I'm getting 404 in GitHub using this link.
Folkert de Vries (Feb 19 2022 at 14:40):most likely you're not added to the repo yet. maybe there is an outstanding invitation ?
Anton (Feb 19 2022 at 14:41):Yep, make sure to check your email
João Alves (Feb 19 2022 at 14:47):Unitil now I only receive this email.
Screenshot-from-2022-02-19-11-46-31.png
Folkert de Vries (Feb 19 2022 at 14:48):the github interface should also show the invitation
Folkert de Vries (Feb 19 2022 at 14:48):somewhere in the top right
João Alves (Feb 19 2022 at 15:03):At the beginning of the email, it said "Invite sent" but I don't know where
João Alves (Feb 19 2022 at 15:04):My GitHub profile is: https://github.com/JADSN
Anton (Feb 19 2022 at 15:49):Can you take a look @Richard Feldman?
Richard Feldman (Feb 19 2022 at 15:55):just sent an invite!
Richard Feldman (Feb 19 2022 at 15:56):maybe it was a copy/paste error on my part, because it said it was invited for the first time - sorry about that!
Trevor Settles (Feb 19 2022 at 16:12):I'm trying to build roc for the first time. I'm on a mac, and it looks like valgrind doesn't support Monterey, or anything since about 2011. According to https://en.wikipedia.org/wiki/Darwin_%28operating_system%29 and https://valgrind.org/info/platforms.html
Is my understanding correct?
João Alves (Feb 19 2022 at 17:03):After exeucte cargo run examples/hello-world/Hello.roc, I am getting this error: failed to run custom build command for roc_builtins v0.1.0` do i need install some dependency?
João Alves (Feb 19 2022 at 17:04):I am running in Linux
Folkert de Vries (Feb 19 2022 at 17:12):what version of zig do you have?
Brendan Hansknecht (Feb 19 2022 at 17:26):@Trevor Settles yeah, sadly no valgrind for Mac. Personally I am on an M1 Mac, and I use nix for all of the dependencies. Makes installing a lot easier.
Folkert de Vries (Feb 19 2022 at 17:32):is there also nothing like valgrind for mac? like, what do you do when there is a memory leak?
Brendan Hansknecht (Feb 19 2022 at 17:39):gdb
Brendan Hansknecht (Feb 19 2022 at 17:39):Watch the program crash cause arm is restrictive about memory.
Folkert de Vries (Feb 19 2022 at 17:42):ok, fun
Brendan Hansknecht (Feb 19 2022 at 17:43):Yeah, haven't found a better way yet
Folkert de Vries (Feb 19 2022 at 17:43):that works for out of bounds memory access but not for leaks
Brendan Hansknecht (Feb 19 2022 at 17:44):Yeah, and misaligned
João Alves (Feb 20 2022 at 11:35):Folkert de Vries said:
what version of zig do you have?
Zip 3.0 (July 5th 2008)
João Alves (Feb 20 2022 at 11:36):Is it possible to make UI using Roc?
João Alves (Feb 20 2022 at 11:37):Like an alternative to elm-ui
Folkert de Vries (Feb 20 2022 at 11:37):zig was not a typo, we need zig 0.8.1 https://ziglang.org/download/
João Alves (Feb 20 2022 at 11:44):Do I need Zig to execute Rust examples?
Folkert de Vries (Feb 20 2022 at 11:49):yes, it is used by the compiler
Brian Carroll (Feb 20 2022 at 13:21):João Alves said:
Is it possible to make UI using Roc?
Like an alternative to elm-ui
No, the language is at an early stage of development and doesn't have anything like that yet. Most of the applications are small demo programs at this stage but we're working on it!
Trevor Settles (Feb 26 2022 at 04:41):I've been working on trying to build roc, but this is the first project that I've tried building from source directly. I'm on a mac, and I have installed llvm v12.0.1, libxkbcommon v1.4.0, and zig v0.9.1 (through brew). I know that the docs say I should use zig version 0.8.0, but I haven't found a way to install that specific version through brew. I have been getting an error (below) that mentions zig, but I am not sure what is causing it. Is it the wrong version of zig?
➜ roc git:(trunk) cargo build
Compiling roc_builtins v0.1.0 (/Users/tws/develop/roc/compiler/builtins)
error: failed to run custom build command for `roc_builtins v0.1.0 (/Users/tws/develop/roc/compiler/builtins)`
Caused by:
process didn't exit successfully: `/Users/tws/develop/roc/target/debug/build/roc_builtins-c5ec60eda6bbac41/build-script-build` (exit status: 101)
--- stdout
cargo:rerun-if-changed=build.rs
Compiling host ir to: /Users/tws/develop/roc/compiler/builtins/bitcode/builtins-host.ll
--- stderr
thread 'main' panicked at 'zig failed: ./build.zig:58:24: error: expected type 'std.build.EmitOption', found 'bool'
obj.emit_llvm_ir = true;
^
/usr/local/Cellar/zig/0.9.1/lib/zig/std/build.zig:1597:28: note: std.build.EmitOption declared here
pub const EmitOption = union(enum) {
^
', compiler/builtins/build.rs:158:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Yes, I believe we haven't yet updated some things to accommodate Zig 0.9.x
jan kili (Feb 26 2022 at 04:42):Zig 0.8.0 or 0.8.1 are required
jan kili (Feb 26 2022 at 04:43):Have you used Nix before?
Trevor Settles (Feb 26 2022 at 04:45):Good to know that about zig. I haven't tried nix yet. I'll give that a go
jan kili (Feb 26 2022 at 04:45):Nix is an OS package manager for Linux and somewhat macOS, it's so friendly
jan kili (Feb 26 2022 at 04:45):I recommend installing it
jan kili (Feb 26 2022 at 04:46):Then, from the root directory of the roc repo, run nix-shell shell.nix
jan kili (Feb 26 2022 at 04:47):You should find yourself in a nested interactive shell with all Roc dependencies installed, ready to cargo run repl :)
Trevor Settles (Feb 26 2022 at 04:59):That did the trick, thanks! I'm in the roc repl!
Michael Mongelli (Mar 08 2022 at 05:38):I joined some time ago and Richard gave me access to the GitHub, but haven’t had a personal computer for a bit. I went on GitHub today to pull but i don’t seem to have access anymore. Is there something I’m missing or do I need to be re-invited?
Brian Parks (Mar 08 2022 at 05:43):Got the repo cloned and building! The README references an example platform for an HTTP server… am I misunderstanding what that means? Is that the wasm platform or is there one that would allow building of web apps?
Brendan Hansknecht (Mar 08 2022 at 05:47):@Michael Mongelli It shouldn't auto remove people, but I am sure that @Richard Feldman can send you a new invite link.
@Brian Parks I think that a few sample web server apps have been played around with in the past, but we don't yet have a web server example. The readme is just listing a potential use case.
Brendan Hansknecht (Mar 08 2022 at 05:48):This is a simple example of a webserver that I was messing around with a long while ago: https://github.com/rtfeldman/roc/pull/1635
Brian Parks (Mar 08 2022 at 05:50):@Brendan Hansknecht thanks. I’ll check that out and then tinker some… maybe with the goal of putting together a basic example…
Michael Mongelli (Mar 08 2022 at 05:56):@Brendan Hansknecht @Richard Feldman my mistake, I do have access, I was just expecting to see it in a different place on GitHub, thanks
Brian Parks (Mar 08 2022 at 06:01):Looks like this PR might cover the web example, but I do see why it wasn’t merged (yet). This might start getting into #contributing territory, but any objections to me starting to build a more sophisticated web framework on top of this platform (i.e. assuming that this will be reasonably API-stable)
Brendan Hansknecht (Mar 08 2022 at 06:07):That example is really simple and would not really be robust enough for most web use cases. I assume that for a proper web server platform, a lot more design work would need to go into the api. Especially when it comes to other types of requests. But if you have a basic enough use case, feel free to use the platform
Brendan Hansknecht (Mar 08 2022 at 06:08):Most likely a more sophisticated web framework would really be it's own platform
Brendan Hansknecht (Mar 08 2022 at 06:08):Also, it was never merged because all examples require testing and testing a webserver is more complicated. I just never got around to adding it and then started working on other things.
Brendan Hansknecht (Mar 08 2022 at 06:09):More or less forgot about it.
Brian Parks (Mar 08 2022 at 06:53):Sounds good. I’ll poke at it over the next couple days and share if I make anything interesting.
Derek Gustafson (Mar 09 2022 at 03:35):How can I get the Roc fmt to run on my code?
Brendan Hansknecht (Mar 09 2022 at 03:40):should just be ./roc format <path to file or folder>
Brendan Hansknecht (Mar 09 2022 at 03:40):or cargo run format <path to file or folder>
Brendan Hansknecht (Mar 09 2022 at 03:42):On that note, we may have a bug with the directory version. Looks like it might try to format all files, not just roc files...mine just failed trying to format the output executable.
Derek Gustafson (Mar 09 2022 at 03:55):That worked for me. Thank you
Jared Cone (Mar 10 2022 at 19:40):Is roc limited to one module per roc file, or can you have multiple modules (or namespaces?) in a single file?
Brian Carroll (Mar 10 2022 at 22:42):A file is a module and a module is a file!
Tom Dohrmann (Mar 11 2022 at 11:26):The way effects are currently implemented, functions in Roc are not pure from the host platform's point of view, are they?
jan kili (Mar 11 2022 at 13:24):I think they are, but are you referring to a specific aspect of their implementation?
jan kili (Mar 11 2022 at 13:27):I think the effects system includes platform-defined wrapper types (i.e. Task) for apps to return, so that apps can purely specify what impure work should be done by the platform.
Tom Dohrmann (Mar 11 2022 at 13:30):I'm referring to the roc_foo_fx_bar functions. Those are obviously not pure and since the Roc applications call those functions, they therefore are also not pure, are they?
Folkert de Vries (Mar 11 2022 at 13:38):not sure what language you're most familiar with, but this is also the case in e.g. elm or haskell
Folkert de Vries (Mar 11 2022 at 13:38):we fix this by always wrapping the result of such functions in an Effect, (or Task/Cmd in elm, IO in haskell)
Tom Dohrmann (Mar 11 2022 at 13:56):Ok, but AFAIK Elm or Haskell don't allow you to implement/switch out the platform. Just thought it could have been nice to have calling into Roc be pure from the platforms point of view.
Folkert de Vries (Mar 11 2022 at 13:56):it is
Folkert de Vries (Mar 11 2022 at 13:57):it just may give you an Effect
Folkert de Vries (Mar 11 2022 at 13:57):which the host then has to evaluate
Tom Dohrmann (Mar 11 2022 at 14:00):so I'd just have to make your own types to do that, wouldn't I?
Tom Dohrmann (Mar 11 2022 at 14:00):This doesn't work with the whole roc_fx_bar thing, does it?
Folkert de Vries (Mar 11 2022 at 14:02):huh?
Folkert de Vries (Mar 11 2022 at 14:02):roc code is always pure. it can however build up a computation (an effect) that the host will evaluate, and that will produce side-effects
Folkert de Vries (Mar 11 2022 at 14:03):much like how in elm you make a Task (pure) which the platform then evaluates (e.g. fire of an http request, impure)
Tom Dohrmann (Mar 11 2022 at 14:07):Ok, I might be missing the part where the host is evaluating the effect. For example in examples/interactive/effects-platform/host.zig where is the host getting and evaluating the getLine effect? Or in other words where is the host calling into roc code which returns an effect and evaluates that effect thus doing side effects?
Folkert de Vries (Mar 11 2022 at 14:18):we have roc__mainForHost_1_exposed_generic(output); which evaluates main, giving a Effect {}
Folkert de Vries (Mar 11 2022 at 14:19):an Effect a is a wrapper around {} -> a
Folkert de Vries (Mar 11 2022 at 14:19):which is forced by call_the_closure(output);
Tom Dohrmann (Mar 11 2022 at 14:30):I see. And call_the_closure calls roc__mainForHost_1_Fx_caller which I assume evaluates the effect?
Tom Dohrmann (Mar 11 2022 at 14:35):And so Effects combined with Effect.after are just _one_ Effect, so roc__mainForHost_1_Fx_caller evaluates all steps one after another without returning to the host, instead of evaluating the first effect and yielding the next Effect to be evaluated?
Jared Cone (Mar 11 2022 at 17:19):(beginner here) My interpretation is Roc is queuing up a chain of side effects that the platform executes. Roc main says "Queue this side effect. When it's done, call this Roc code which will queue another side effect. When that's done, call this other Roc code..."
When Roc executes the call to Stdout.line it isn't executing println right then. It's like passing back a lambda to the platform, then the platform executes it.
Folkert de Vries (Mar 11 2022 at 17:25):roc__mainForHost_1_Fx_caller calls the {} -> a function. That will perform the main function, so it does sort of do all the effects at once. During this call no interaction with the platform happens.
Folkert de Vries (Mar 11 2022 at 17:26):but, the idea is that we can e.g. call that function twice, or in a loop
Last updated: Jul 26 2025 at 12:14 UTC