[BUG] Transforming to a different type in Typescript?

[bastiankoetsier]

Describe the bug
First of all: Thank you very much for this awesome library!
I was trying to use it in typescript but I have a small issue where it is not possible(?) to use transform to map from the InputType to a different OutputType having same properties but different types (sorry for the bad wording, hopefully the example makes this more clear 😅)

Parsing or Formatting?

• Formatting
• Parsing

To Reproduce
My code:

type InputRow = {
  clicks: string;
};

type OutputRow = {
  clicks: number;
};
...
  return new Promise((resolve, reject) => {
    const result: any[] = [];
    fs.createReadStream(path.resolve(__dirname, inputFile))
      .pipe(
        parse<InputRow, OutputRow>({ headers: true })
      )
      .on("error", (error: Error) => console.error(error))
      .on("data", (row: any) => {
        result.push(row);
      })
      .transform((data: InputRow): OutputRow => {
        return {
          clicks: parseInt(data.clicks, 10),
         };
      })
      .on("end", () => resolve(result));
  });

I was checking the type-definitions and found

export declare const parse: <I extends Row, O extends Row>...

Is there any reason why O needs to extends Row?

Expected behavior
The given output type should not extend Row
Screenshots

If you have any questions, just let me know!

[doug-martin]

I added this in v4.2.0 let me know if you run into any additional issues.

Thanks again!

[bastiankoetsier]

Works like a charm! Thanks for the very quick response @doug-martin !