(

(let config (DataSource 'config))
(let res_sink (DataSink 'result))

### Tuple
(let srcType (VariantType (TupleType (DataType 'Int32) (DataType 'String))))
(let targetType (VariantType (TupleType (DataType 'Uint8) (DataType 'Utf8))))

# Variant<Tuple<Int32, String>> -> Variant<Tuple<Uint8, Utf8>>? (good)
(let value (Variant (String 'one) '1 srcType))
(let cast (StrictCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

# Variant<Tuple<Int32, String>> -> Variant<Tuple<Uint8, Utf8>>? (null)
(let value (Variant (String '"garbage\xff") '1 srcType))
(let cast (StrictCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

### Struct
(let srcType (VariantType (StructType '('a (DataType 'Int32)) '('b (DataType 'String)))))
(let targetType (VariantType (StructType '('a (DataType 'Uint8)) '('b (DataType 'Utf8)))))

# Variant<Struct<Int32, String>> -> Variant<Struct<Uint8, Utf8>>? (good)
(let value (Variant (Int32 '1) 'a srcType))
(let cast (StrictCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

# Variant<Struct<Int32, String>> -> Variant<Struct<Uint8, Utf8>>? (null)
(let value (Variant (Int32 '"-1") 'a srcType))
(let cast (StrictCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

(let world (Commit! world res_sink))

(return world)

)