[Rust] Can't get minimal example to run

[Freymaurer]

Description

I should start with i have never done anything with/in rust before.

Here is what i did trying to setup fable-rust.

1. Install DOWNLOAD RUSTUP-INIT.EXE (64-BIT
2. create new folder
3. dotnet new tool-manifest
4. dotnet install fable
5. create Cargo.toml (See Repro code)
6. create test.fsx (See Repro code)
7. run dotnet fable test.fsx --lang rust -e rs --noCache, creating test.rs.
8. cargo clean
9. cargo build

get the following error:

Repro code

//test.fsx
#r "nuget: Fable.Core, 4.2.0"

[<EntryPoint>]
let main argv =
  printfn "Hello World!"
  0

[package]
name = "fable-rust-sample"
version = "0.1.0"
edition = "2021" 

[[bin]]
name = "test"
path = "test.rs"

[dependencies]
fable_library_rust = { path = "./fable_modules/fable-library-rust" }

Copying the code from test.fsx into fable repl does not print "Hello World!" either.

Expected and actual results

I would expect "Hello World!" console output.

Related information

• Fable version: 4.6.0
• Operating system: Windows 11

[smoothdeveloper]

@Freymaurer can you replace the script with a consoleapp fsproj?

dotnet new consoleapp -lang f#

in the same directory and moving your code

then adjusting the Cargo.toml like the screenshot below, then

dotnet fable . --lang rust

then

cargo run

[MangelMaxime]

We also have a setup guide for Rust here and it is indeed using fsproj.

I know that in past fsx support was difficult because it is not real project and also it has less love/tests for it because the main usage of F# is via project file.

[Freymaurer]

Ah yes i see, it worked with a .fsproj. Will there be .fsx support in the future? Just asking out of interest

[Freymaurer]

One more issue i found when testing async:

//Program.fs
let asynWaitNPrint(wait: int) = async {
  do! Async.Sleep(wait)
  printfn "Hello World!"
  return 0
}

[<EntryPoint>]
let main argv =
  asynWaitNPrint 1000
  |> Async.RunSynchronously

Calling the output with cargo run results in:

   Compiling fable-rust-sample v0.1.0 (C:\Users\Kevin\Desktop\fable_transpile\rust)
error[E0432]: unresolved import `fable_library_rust::Async_`
  --> Program.fs.rs:16:33
   |
16 |         use fable_library_rust::Async_::Async;
   |                                 ^^^^^^ could not find `Async_` in `fable_library_rust`

error[E0432]: unresolved import `fable_library_rust::Async_`
  --> Program.fs.rs:17:33
   |
17 |         use fable_library_rust::Async_::runSynchronously;
   |                                 ^^^^^^ could not find `Async_` in `fable_library_rust`

error[E0432]: unresolved import `fable_library_rust::Async_`
  --> Program.fs.rs:18:33
   |
18 |         use fable_library_rust::Async_::sleep;
   |                                 ^^^^^^ could not find `Async_` in `fable_library_rust`

error[E0432]: unresolved import `fable_library_rust::AsyncBuilder_`
  --> Program.fs.rs:19:33
   |
19 |         use fable_library_rust::AsyncBuilder_::bind;
   |                                 ^^^^^^^^^^^^^ could not find `AsyncBuilder_` in `fable_library_rust`

error[E0432]: unresolved import `fable_library_rust::AsyncBuilder_`
  --> Program.fs.rs:20:33
   |
20 |         use fable_library_rust::AsyncBuilder_::delay;
   |                                 ^^^^^^^^^^^^^ could not find `AsyncBuilder_` in `fable_library_rust`

error[E0432]: unresolved import `fable_library_rust::AsyncBuilder_`
  --> Program.fs.rs:21:33
   |
21 |         use fable_library_rust::AsyncBuilder_::r_return;
   |                                 ^^^^^^^^^^^^^ could not find `AsyncBuilder_` in `fable_library_rust`

For more information about this error, try `rustc --explain E0432`.
error: could not compile `fable-rust-sample` (bin "Program") due to 6 previous errors

looking like this in vs code

[ncave]

@Freymaurer A lot of fable-libraty-rust implementations are opt-in and feature flagged, to minimize default library size and compilation time. For Async, you need to add this feature in your Cargo.toml:

[dependencies]
fable_library_rust = { path = "./fable_modules/fable-library-rust", features = ["threaded"] }

The full list of features is available here.

But yes, async support is still somewhat sketchy at the moment, for example Async.Sleep() is not implemented yet.
Contributions are very welcome, and no contribution is too small.

[Freymaurer]

I see, yeah i wanted to add Rust support to Fable.Pyxpecto, as it supports js, ts, py and .net in the latest beta release.

Sadly i have 0 knowledge about rust and would be of no real help implementing. Just wanted to increase support.

[Freymaurer]

I think this issue can be closed for now :)