Fable 1.2.4 broke importMember function

[inosik]

Description

I updated my VSCode extension sample to Fable 1.2.4 from 1.2.3 and this broke the importMember function. If I change my code to use the import function or the Import-Attribute it works.

Repro code

Clone the repository from above and checkout the fable-broken-import-member branch. Then follow the instructions from the readme.

Expected and actual results

This is what I get:

./src/wordcount.fsproj → ./out/extension.js...
fable: Compiled src\wordcount.fsproj
[!] (fable plugin) Error: D:/projects/experiments/fable/vscode-rollup-sample/src/extension.fs(1,1): error FABLE: `importMember` must be assigned to a variable
 Make sure Fable server is running on port 61225
src\extension.fs
Error: D:/projects/experiments/fable/vscode-rollup-sample/src/extension.fs(1,1): error FABLE: `importMember` must be assigned to a variable
 Make sure Fable server is running on port 61225
    at error (D:\projects\experiments\fable\vscode-rollup-sample\node_modules\rollup\dist\rollup.js:185:14)
    at Promise.resolve.then.catch.err (D:\projects\experiments\fable\vscode-rollup-sample\node_modules\rollup\dist\rollup.js:9182:6)

Related information

• Fable version (dotnet fable --version): 1.2.4
• Operating system: Windows 7 x64

[inosik]

I just tried to import a string with importMember, and it worked. Looks like importing (curried?) functions is broken.

[inosik]

Looks like importing (curried?) functions is broken.

Doing this change makes it work again:

diff --git a/src/extension.fs b/src/extension.fs
index d532c07..eff85ce 100644
--- a/src/extension.fs
+++ b/src/extension.fs
@@ -8,7 +8,7 @@ open Fable.Import.vscode
 [<Emit("$0.match(/\w+/g)")>]
 let wordsIn (str : string) : obj = jsNative

-let formatCount : int -> string = importMember "./formatter"
+let formatCount : System.Func<int, string> = importMember "./formatter"

 let activate (context : ExtensionContext) =
   let sb = window.createStatusBarItem StatusBarAlignment.Left
@@ -23,7 +23,7 @@ open Fable.Import.vscode
     | Some e ->
       let d = e.document
       if d.languageId = "markdown" then
-        sb.text <- d |> wordCount |> formatCount
+        sb.text <- d |> wordCount |> formatCount.Invoke
         sb.show ()
       else
         sb.hide ()

[Zaid-Ajaj]

@inosik What about the following? (havn't testsed it tho)

let formatCount (n: int) : string = importMember "./formatter"

I thought this should work, then you wouldn't have to call .Invoke on the application

[inosik]

@Zaid-Ajaj Yes, that works as well. But I'd still consider this a regression, because that caused existing code to break.

[alfonsogarciacaro]

Though it's true that let formatCount (n: int) : string = importMember "./formatter" is the preferred way now as @Zaid-Ajaj points out, it's also true this is indeed a regression. Thanks for pointing out that it happened after updating to 1.2.4 @inosik, this probably means this commit or this one are the culprits, I'll check :+1: Actually I hit something like that in one of my projects though, weird enough, I wasn't using 1.2.4.

[inosik]

I don't remember why I did int -> string in the first place :smile: And I agree that giving names to the arguments is probably more user-friendly, at least in this case.

[alfonsogarciacaro]

Sorry @inosik, can you please check if this is fixed with Fable 1.3?

[inosik]

No, unfortunately it's still the same with 1.3.0.

The transformation which happens in this else block is missing in the then block above. I think I fixed it, let me wrap it up cleanly and create a PR.

[inosik]

See #1239.