re: Let the compiler do the work for you! VIEW POST


I've been having doubts about the use of deriving when it comes to code style. It sure as hell is convenient but it hides information from the programmer. It would cause problems for instance if for some reason someone were to switch the order of left and right branches (ignoring why the hell someone would do that). Admittedly this is also an argument for records.

For Aeson in particular I'd just rather resort to declaring my own instances.

What are your thoughts on this issue?


I really advocate the use of deriving as much is possible. DervingVia basically allows you to create a standard set of instances you can derive for other data types. Handwritten instances should IMO be kept as small as possible.
As said, more code always means more bugs and it makes the code harder to read. The derived instances always behave the same, so it is independent of local conventions. Also, due to the laws attached to the classes, most of the time, there is only one lawful instance for a given datatype

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