Can this not be done with the HList code? I am pretty sure you should be able to map projections over HLists of HLists... (although the HList generic map is a bit ugly, requiring instances of the Apply class). Actually you should look in the OOHaskell paper (if you haven't already) where it discusses using "narrow" to allow homogeneous lists to be projected from heterogeneous ones... Keean. John Meacham wrote:
another thing is that for any record syntax, we would want higher order versions of the selection, setting, and updating routines. A quick perusal of my source code shows over half my uses of record selectors are in a higher order fashion. (which need to be generated with DrIFT with the current syntax)
I mean something like
map (.foo) xs to pull all the 'foo' fields out of xs. (using made up syntax)
or
map (foo_s 3) xs
to set all the foo fields to 3. (using DrIFT syntax)
John