(

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

(let targetType (TupleType (DataType 'Uint8) (DataType 'Utf8)))

# (Int32, String) -> (Uint8, Utf8) [good]
(let value '((Int32 '1) (String 'one)))
(let cast (SafeCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

# (Int32, String) -> (Uint8, Utf8)? [null]
(let value '((Int32 '1) (String '"garbage\xff")))
(let cast (SafeCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

# (Int32?, String???) -> (Uint8??, Utf8?)? [good]
(let targetType (TupleType (OptionalType (OptionalType (DataType 'Uint8))) (OptionalType (DataType 'Utf8))))
(let value '((Just (Int32 '1)) (Just (Nothing (OptionalType (DataType 'String))))))
(let cast (SafeCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

# (Int32?, String???) -> (Uint8??, Utf8?)? [null]
(let value '((Just (Int32 '1)) (Nothing (OptionalType (OptionalType (DataType 'String))))))
(let cast (SafeCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

# (Int32?, String???) -> (Uint8??, Utf8?)? [null]
(let value '((Just (Int32 '-1)) (Just (Nothing (OptionalType (DataType 'String))))))
(let cast (SafeCast value targetType))
(let world (Write! world res_sink (Key) cast '('('type))))

(let world (Commit! world res_sink))

(return world)

)