improve the macro rules for impl_primitive_form_variant for timestamp

Author: klion26

parquet-variant-compute/src/type_conversion.rs

@@ -56,7 +56,7 @@ macro_rules! impl_primitive_from_variant {
             }
         }
     };
-    ($arrow_type:ty $(, $variant_method:ident => $cast_fn:expr )+ ) => {
+    ($arrow_type:ty, $( $variant_method:ident -> $cast_fn:expr ),+ $(,)?) => {
         impl TimestampFromVariant for $arrow_type {
             fn from_variant(variant: &Variant<'_, '_>) -> Option<Self::Native> {
                 $(
@@ -88,11 +88,11 @@ impl_primitive_from_variant!(
 );
 impl_primitive_from_variant!(
     datatypes::TimestampMicrosecondType,
-    as_timestamp_micros => |t| t);
+    as_timestamp_micros -> |t| t);
 impl_primitive_from_variant!(
     datatypes::TimestampNanosecondType,
-    as_timestamp_micros => |t| 1000 * t,
-    as_timestamp_nanos => |t| t);
+    as_timestamp_micros -> |t| 1000 * t,
+    as_timestamp_nanos -> |t| t);
 
 /// Convert the value at a specific index in the given array into a `Variant`.
 macro_rules! non_generic_conversion_single_value {