Adding Decimal type

[Bidek56]

Adding Polars Decimal type, although this functionality is considered unstable in Polars ATM. To close #209

[Bidek56]

@universalmind303 Would you know how to fix this method for Decimal type? Thx

impl FromNapiValue for Wrap<ChunkedArray<Int128Type>> {
    unsafe fn from_napi_value(env: sys::napi_env, napi_val: sys::napi_value) -> JsResult<Self> {
        let arr = Array::from_napi_value(env, napi_val)?;
        let len = arr.len() as usize;
        let mut builder = PrimitiveChunkedBuilder::<Int128Type>::new("", len);
        for i in 0..len {
            match arr.get::<BigInt>(i as u32) {
                Ok(val) => match val {
                    Some(v) => {
                        let (v, _b) = v.get_i128();
                        builder.append_value(v)
                    }
                    None => builder.append_null(),
                },
                Err(_) => {
                    builder.append_null()
                }
            }
        }
        Ok(Wrap(builder.finish()))
    }
}

[Bidek56]

@flisky Would you know how to fix this method for Decimal type? Thx

[flisky]

You have to keep scale at least, although the type declared as Option<usize>, it's required actually. The Option is just user faced, and it should be resolved as soon as possible.

[Bidek56]

@stinodego Would you know how to fix this method for Decimal type? Thx

[stinodego]

I don't know, but looks like you're not currently implementing it for Decimal. You're implementing on Int128 when you should be implementing on Logical<DecimalType, Int128Type>.