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queil / fsc-host

Extend your F# apps with F# scripts
The Unlicense
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fsc-host in WebAssembly #13

Open harrisse opened 1 year ago

harrisse commented 1 year ago

Is it possible to run fsc-host in WebAssembly?

I'm trying to invoke fsc-host with CompilerHost.getAssembly Options.Default (Inline text) but am hitting the following exception:

System.TypeInitializationException: The type initializer for '<StartupCode$FSharp-Compiler-Service>.$FSharpCheckerResults' threw an exception.
System.NullReferenceException: Object reference not set to an instance of an object.

Googling the error took me to https://github.com/dotnet/fsharp/issues/11966 which I saw you had left a comment on, so I figured you might know something one way or the other 😄

This project got fsc working in the browser a while back but the approach no longer works in .net 7. I was able to make some progress on their approach by copying dlls from the browser cache to the filesystem, but was never able to get fsc to recognize symbols from -r:'d dlls.

Thanks!

queil commented 1 year ago

Hi @harrisse, I'll take a look if anything can be done here.

queil commented 1 year ago

Hi @harrisse I know it has been ages but do you have any repro for this? I am not super familiar with WebAssembly so a test project would help.

queil commented 7 months ago

Closed due to lack of interest.

PawelStadnicki commented 7 months ago

I'm very interested in this one. However if fsc-host uses fsi under the cover, it will not work, there will be many unsupported operation errors while speaking to console in/out, file etc. I created a ticket to address that but I think it would be easier to write some FsiLight version. And with .NET 9 is coming real multi-threading (tentative) :)

queil commented 7 months ago

So, fsc-host doesn't use fsi. It uses FSharp.Compiler.Service which under the hood uses fsc.exe (i.e. it requires the dotnet sdk). Web assembly has never been a priority for me personally and I am not even sure how people use F# in web assembly. However, if fsc-host could add any value to that scenario I am open to suggestions.

PawelStadnicki commented 7 months ago

My interest in using some sort of fsc-host/fsi-light in webassembly is to enable writing and executing a custom DSL code by the application users to extend the application features for their personal needs.

For that I'm using .net interactive that has a F# kernel, however that uses fsi which is not wasm friendly.

It all works when Blazor (wasm for .NET) runs in server mode but not in a client mode. And wasm is getting real multi-threading support with .NET 9 :)

Why I need it? At least for 2 reasons:

So I see two options:

The later could be done starting from scratch or extending fsc-host.

Currently when I run example of fsc-host in wasm I'm getting

Unhandled exception rendering component: Could not find a part of the path '/plugins/default/plugin.fsx'.

That most likely can be eliminated as I have seen it support plain string body as well. Not sure if wasm will allow to use fsc.exe. Even thought, I would still need some sort of interactivity to query the bounded values and run several snippets in a session mode to make it possible to mix with other languages/kernels of .net interactive (C#, AI).

I will explore more.

queil commented 7 months ago

run example of fsc-host in wasm I'm getting

Would you be able to share a minimum example of how you run it in wasm? A repo/Dockerfile would be great.

queil commented 7 months ago

Also I think fsc-host was never meant to be used in interactive contexts. So you may actually be better with an fsi-light approach.

evelant commented 2 months ago

My interest in using some sort of fsc-host/fsi-light in webassembly is to enable writing and executing a custom DSL code by the application users to extend the application features for their personal needs.

@PawelStadnicki I'm also interested in this exact use case. Have you made any progress on achieving this?

PawelStadnicki commented 2 months ago

hi @evelant I did a more detailed research and ... we have to wait for MSFT

Fsi is currently not wasm-friendly, it has a lot dependencies on a local files etc.

Maybe there are other ways than using Fsi but I don't know them and I want to use .NET Interactive (to have a polyglot programming capabilities with JS and Python). .NET Interactive uses Fsi in the F# Kernel.

I asked the F# team to make Fsi warm-friendly, don't know when it is going to happen.

Moreover, real multithreading in wasm is postponed until .NET 10 (there is a great progress on that but the amount of changes and backward compatibility was a huge effort to make it with .NET 9).

Last but not least, when it is ready, it will require a vast amount of F# services to be loaded into wasm as well, making it slow to load - but only on a first load. Not that tragic, but important (still I'm not sure about the overall performance having so many stuff in the web cache)

Summary, I'm waiting for: