Data.Fixed.Fixed constructor

Jules Bean jules at
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.


More information about the Libraries mailing list