jules at jellybean.co.uk
Thu Jul 23 09:07:36 EDT 2009
Ashley Yakeley wrote:
> I'm currently working on updating the Data.Fixed module in base. I am
> adding Typeable and Data instances (automatically derived), and several
> new HasResolution types (including one for 10^-2, monetary currencies
> being an obvious Fixed use).
Is an automatic Data instance wise?
Morally speaking does a Data.Fixed really "include" a Integer?
Compare the question: should the automatic Data instance for Complex a
be used, since this exposes the fact that Complex is stored using two
components in real/imaginary components?
I think that abstract types like Complex and Fixed should be treated as
atoms by Data rather than being traversable, but I'm not sure.
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