[TypeScript] Option<> to Optional Parameter misses unwrap.

[Freymaurer]

Description

I am currently working on typescript transpilation for our library ARCtrl. I want to do this to offer type support for the js native release.

Sadly i get around 850 errors, which i am now trying to resolve one by one. I started investigating in:

dist/ts/Spreadsheet/Metadata/Publication.ts:32:65 

error TS2345: Argument of type 'Option<string>' is not assignable to parameter of type 'string | undefined'.

32     const status_1: OntologyAnnotation = new OntologyAnnotation(status, statusTermSourceREF, statusTermAccessionNumber);

And i found the following:

export function fromString(pubMedID: Option<string>, doi: Option<string>, author: Option<string>, title: Option<string>, status: Option<string>, statusTermSourceREF: Option<string>, statusTermAccessionNumber: Option<string>, comments: Comment$[]): Publication {
    const status_1: OntologyAnnotation = new OntologyAnnotation(status, statusTermSourceREF, statusTermAccessionNumber);
    const pubMedID_1: Option<string> = map<string, string>(URIModule_fromString, pubMedID);
    const status_2: Option<OntologyAnnotation> = Option_fromValueWithDefault<OntologyAnnotation>(new OntologyAnnotation(), status_1);
    return Publication.make(pubMedID_1, doi, author, title, status_2, comments);
}

I tried to replicate this behavior on the Fable REPL, but the REPL transpiles it using unwrap (see REPL below).

Adding unwrap by hand to the typescript code seems to resolve the issue. Now i am not sure why this happens.

The F# code in question can be found: here

Repro code

REPL.

Expected and actual results

Please provide the expected and actual results.

Related information

• Fable version: dotnet fable --version : 4.19.2
• Operating system : Win 11 Pro

[ncave]

@Freymaurer Yes, looks like it doesn't unwrap when you omit some of the optional parameters.
To reproduce, add another optional argument, but keep the caller the same, e.g.:

[<AttachMembersAttribute>]
type MyTestClass(?nameOption: string, ?otherOption: int) =
    member val Name = defaultArg nameOption "Kevin" with get, set

let testCreate (nameOption: string option) =
    MyTestClass(?nameOption = nameOption)

[HLWeil]

Thank you for the quick fix, @ncave!

For when is the next release containing this fix planned?

[MangelMaxime]

It is available in 4.19.3

[goswinr]

@MangelMaxime @ncave I am also working on a library for both TS and .NET.
I have a lot of compile errors when generating d.ts definitions with TSC after fable compile to TS.
But so far I could just ignore them and use the generated definitions with the fable compiled JS. 😅
Is there any guide or example on how to best set up tsconfig.json for generating d.ts files with via fable and TSC ?

[Freymaurer]

Have a look here, that is at least what worked for me 🙂 but i am by no means an expert for ts.