是否有用于 Promises 的计算表达式构建器？

Question

async function showSampleText(context: vscode.ExtensionContext): Promise<void> {
    let sampleTextEncoded = await vscode.workspace.fs.readFile(vscode.Uri.file(context.asAbsolutePath('sample.txt')));
    let sampleText = new TextDecoder('utf-8').decode(sampleTextEncoded);
    let doc = await vscode.workspace.openTextDocument({ language: 'plaintext', content: sampleText });
    vscode.window.showTextDocument(doc);
}

我将上面的 Typecript 片段翻译成下面的 Fable 代码。

type ITextDecoder =
    abstract member decode: ?input: Uint8Array * ?options: {| stream : bool |} -> string

[<Emit("new TextDecoder([=11=])")>]
let TextDecoder label : ITextDecoder = jsNative

let show_sample_text (ctx : Vscode.ExtensionContext) = 
    async {
        let! sampleTextEncoded = Vscode.workspace.fs.readFile(statics.Uri.file(ctx.asAbsolutePath("sample.txt"))) |> Async.AwaitPromise
        let sampleText = TextDecoder("utf-8").decode(sampleTextEncoded);
        let! doc = workspace.openTextDocument(options= !!{| language="plaintext"; content=sampleText |}) |> Async.AwaitPromise
        let! _ = window.showTextDocument(document=doc,options=undefined) |> Async.AwaitPromise
        return ()
    } |> Async.StartAsPromise

我在 Async 和 Promise 之间显式转换的方式让我很困扰。某处是否有专门针对 Promises 的构建器？

Answer 1

Fable 通过 Fable.Promise 包支持 promise。

如果您将 Fable.Promise 包添加到您的项目中，那么您可以这样做：

let private getRandomUser () = promise {
    // Do something here
    // ...
    return ()
}

是否有用于 Promises 的计算表达式构建器？

Is there a computation expression builder for Promises?

promise

fable-f#