Re: Proposal: Add Data instance for Const

On Nov 2, 2016, at 8:40 AM, Ryan Scott wrote:

GHC Trac #12438 [1] exists because there's no Data instance for Const in base. I found this quite surprising, since we have Data instances for just about every other type combinator out there (Identity, Sum, Product, Compose, etc.), but not for Const. The fix for #12438 would be quite simple: I propose we add

deriving instance (Data a, Data b) => Data (Const a b)

to Data.Data in base. Any objections?

Seems like an oversight worth correcting to me. -- Eric