[GitHub] [arrow-rs] shepmaster edited a comment on pull request #984: Add scalar comparison kernels for DictionaryArray

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shepmaster edited a comment on pull request #984:
URL: https://github.com/apache/arrow-rs/pull/984#issuecomment-992806010


   Ah:
   
   > the way you have this function with a single `T` generic parameter means one could not compare a `DictionaryArray<Int8>` (aka that has keys / indexes of `Int8`) that had values of type `DataType::Unt16`
   
   Perhaps one possibility would be to have a trait that maps in the reverse direction? Something like
   
   ```rust
   trait IntoArrowNumericType {
       type Arrow: ArrowNumericType;
   }
   
   impl IntoArrowNumericType for u8 {
       type Arrow = UInt8Type;
   }
   
   pub fn eq_dict_scalar<K, T>(
        left: &DictionaryArray<K>,
        right: T,
    ) -> Result<BooleanArray>
    where
        K: ArrowNumericType,
        T: IntoArrowNumericType,
    { todo!() }
   ```
   
   


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