I would like to add an F# REPL to my application for live debugging purposes. I am looking at the source code for fsi.exe (F# Interactive) and there is a ton of stuff going on that looks like it pokes around with F# compiler internals. I cannot get this same code to compile in the context of our application because of this.
Is there a nice simple example of implementing an F# REPL somewhere? I would have hoped for this to be fairly easy.
The short answer is that F# (unfortunatelly) doesn't currently provide any API for hosting F# Interactive in your applications. There are a lot of people asking for this - see for example this SO question.
There are essentially two things you could do about that:
You can modify the open-source release and compile fsi.exe as some DLL library that would provide the API you need. This isn't simple task - F# Interactive is tightly bound with the compiler (it compiles code you enter on the fly), but it should be doable to encapsulate the types implementing REPL into some type you could call (But you cannot just take some file out of it - you need to compile entire F# to get this working).
You can run fsi.exe as a separate process as Visual Studio does and send commands to it using standard input/output. You can get some more flexibility by loading your library when fsi.exe starts. The library could use .NET Remoting to connect back to your application and expose some data.
Unfortunatelly, these two options are probably the only things you can do at the moment.
EDIT I was thinking that I already answered this question somewhere (perhaps in email), but couldn't
find it! Thanks to Mauricio who found the exact duplicate (even with my duplicate answer... Doh!)
I've written a series of blog posts about using the open source F# interactive executable inside and WPF application.
The code base is available on github - https://github.com/oriches/Simple.Wpf.FSharp.Repl
The series of blog posts are:
http://awkwardcoder.blogspot.co.uk/2013/12/simple-f-repl-in-wpf-part-1.html
http://awkwardcoder.blogspot.co.uk/2013/12/simple-f-repl-in-wpf-part-2.html
http://awkwardcoder.blogspot.co.uk/2013/12/simple-f-repl-in-wpf-part-3.html
The final post is to follow soon.
Related
I am developing a asp.net web app enabling users to submit F# code, which should be dynamically compiled and executed on the server. I was thinking of either hosting the F# compiler in the web app using the approach shown here:
https://fsharp.github.io/FSharp.Compiler.Service/compiler.html
Or use F# interactive: http://fsharp.github.io/FSharp.Compiler.Service/interactive.html
The idea would be to dynamically compile the F# code and then load it as an assembly in c# or have F# interactive interpret the code. However, my main concern is security and how to stop the end user from executing arbitrary code. Is there an easy way to restrict this? Thanks!
This is an old question and things have considerably changed since it was asked. Now the Fable team have managed to run the F# compiler inside of a web-worker, removing the need to execute code on the server-side. This side-steps all of the security concerns around executing untrusted code.
You can try out the REPL here.
You can view the source-code here.
In this article it says: "The Dart VM reads and executes source code, which means there is no compile step between edit and run.". Does that mean that you can exchange source-code on the fly in a running Dart system like in Erlang? Maybe the compiler is removed from the runtime system and then this is no longer possible. So that's why I'm asking.
Dart is run "natively" only in Dartium, which is a flavour of Chrome with DartVM. When you develop an application you still need to compile it it to JavaScript. This way you get fast development lifecycle and in the end you can compile code to JS. Because it's compiled code there is lots more room for compiler to run optimisations on the code. So from my perspective, the compiler is still there and I don't think you would be able to replace code at runtime.
You can send around source code and run it, but it would need to be in a separate isolate. Isolates do have some relationship to Erlang concepts.
The Dart VM doesn't support hot swapping (Called live edit in V8). However, based on mailing list discussions, it sounds like this is something that the authors do want to support in the future.
However, as the others have mentioned, it is possible to dynamically load code into another isolate.
Is there a REPL for Dart to experiment with?
I tried inputing dart code in DevTools in Dartium and that also didn't work.
So I couldn't find an easy way to play with various APIs in dart.
I tried inputing dart code in devtools in Dartium and that also didn't
work.
I'm very new to Dart, but something I came across was that you CAN evaluate code in Dartium. In order to do so, you must first load a page with Dart code in it and then toggle this selector in the console from "javascript page context" to one that references a Dart package or Dart code.
Once you do that you should be able to execute Dart in the console:
As a VIM user, I hardly have to open the Dart Editor now :). I should also mention that breakpoints, hovering over stepped into code to get variable details, navigating the call stack, and some level of intellisense in the console also work. I couldn't get conditional breakpoints to work, though.
Though it is not really a REPL, you may find the Try Dart online tool useful for playing around. It's a bit slow, since it is actually compiling the Dart code to JavaScript in order to have it work within the browser.
There is also a console that someone built, which is probably better if you're looking for a real REPL, but it requires a bit of setup.
There is an announcement about REPL for Dartium - see Nathanial's comment below. There are plans for Smalltalk like super-REPL. Here is what Gilad Bracha (member of the Dart team at Google) wrote on this subject in Is there a REPL or console for Dart:
"I don't see this as a language question at all. It is a matter of tooling and reflective library support. With proper mirror builder APIs, building a REPL would be trivial. As it sands right now, it can be quite challenging. And of course, REPL is not the ultimate goal - there are more advanced interactive tools, like workspaces in Smalltalk/Self/Newspeak, where you not only evaluate things interactively at some top level, but can inspect the resulting objects, evaluate within the scope of an individual declaration or object etc. I am sure we will get there in time - and i much prefer sooner than later."
The correct answer is https://dartpad.dev/
That site didn't exist when the other answers were posted in 2013, but you've stumbled on this post after 2020. And now you know. https://dartpad.dev allows you to create and share new Dart snippets and even put them in a Flutter app running online. Very, very cool!
Since 2022.10.22, there is a REPL for Dart: https://github.com/fzyzcjy/dart_interactive :)
Features:
Use any third-party package freely
Auto hot-reload code anywhere, with state preserved
Supports full grammar in REPL
Play with existing code side-by-side
Disclaimer: I wrote that package.
I want to write a simple editor with basic autocomplete functionality for the Go language as a pet project. How would one go about doing it? I took a look at the Go plugins for Eclipse and IntelliJ, but they were too big for me to comprehend (not to mention getting one to compile).
The Go standard library offers the building blocks for a Go parser which
you can use to parse the source files and look for function definitions and the like.
There's also the godoc command which
already does what you want: extracting method definitions and it's documentation. You may look in the
source code to see how godoc is
working or use godoc directly.
This editor written in Go projects has a manageable amount of code,
you may look into it.
The de facto standard approach to this problem is to use nsf's gocode. I have tried it only in Vim - it works very well.
Even though there's ready made support for specific editors, gocode is not editor specific. It's a daemon with a communication protocol. It is thus usable from any program.
Years ago, I wrote a code template that took a few simple parameters (points) and produced a class skeleton. Since some of the method bodies had code in them, I couldn't call InvokeClassCompletion and just placed the implementations with the declarations (user had to move them).
It has occurred to me that I can write a code template script engine to insert these methods in the correct position, but I don't see how I'm supposed to navigate the file. There are declarations for IOTAEditReader and IOTAEditWriter in ToolsAPI.pas, but I'm guessing there is a step missing - certainly I don't need to manually parse the Delphi code just to find the implementation section?
Does anyone have experience with it?
The IDE has plenty of parsers in it, but not one is made available for IDE plugins (ToolsAPI). So you have to write your own parser or use an existing one like http://delphiblog.twodesk.com/using-the-castalia-delphi-parser
You might find that GExperts or CNPack contains almost all the code you need, in one of its editor wizards.
If not, then, those two are the best reference I know for writing IDE plugins. As far as writing parsers, see Andreas' answer.
If you just want better code templates, you could consider buying Castalia, as it has an improved code template feature over the builtin delphi IDE plugin features. Castalia internally uses the Castalia delphi parser mentioned by andreas. It's quite good.