Re: [Haskell-cafe] Is there a way to make this code compose generic ?

24 Apr 2025

      Hello,

I am back to work :)

I started to implement a bunch of DataSources.

Which are like this

data family DSDegree (k ∷ DSKind)
data instance DSDegree DSPath
    = DataSourcePath'Degree'Hdf5 (DSWrap_ (DSDataset Z Double) DSPath)
    | DataSourcePath'Degree'Const Degree
    deriving (Generic, Show, FromJSON, ToJSON)

data instance DSDegree DSAcq
    = DataSourceAcq'Degree'Hdf5 (DSWrap_ (DSDataset Z Double) DSAcq)
    | DataSourceAcq'Degree'Const Degree
    deriving Generic

instance DataSource DSDegree where
  withDataSourceP f (DataSourcePath'Degree'Hdf5 p) g
    = withDataSourcesP f p $ λp' → g (DataSourceAcq'Degree'Hdf5 p')
  withDataSourceP _ (DataSourcePath'Degree'Const d) g = g (DataSourceAcq'Degree'Const d)

In order to use the generic implementation of ds'Shape, I need to add plenty of

instance GDataSourceAcq (K1 R Degree) where
    g'ds'Shape _ = pure shape1

Is it possible to says, the default implementation of the generic method is pure shape1
So I just need to implement the non shape1 methodes.

Thanks

Fred

generic'ds'Shape ∷ ( MonadSafe m
                   , Generic (d DSAcq)
                   , GDataSourceAcq (Rep (d DSAcq))
                   )
                 ⇒ d DSAcq → m DataSourceShape
generic'ds'Shape = g'ds'Shape ∘ from

class GDataSourceAcq dataAcq where
   g'ds'Shape ∷ MonadSafe m ⇒ dataAcq x → m DataSourceShape

instance GDataSourceAcq f ⇒ GDataSourceAcq (M1 i c f) where
	g'ds'Shape (M1 f) = g'ds'Shape f

instance (GDataSourceAcq f, GDataSourceAcq f') ⇒ GDataSourceAcq (f :*: f') where
   g'ds'Shape (f :*: f') = liftA2 combine'Shape (g'ds'Shape f) (g'ds'Shape f')

instance (GDataSourceAcq f, GDataSourceAcq f') ⇒ GDataSourceAcq (f :+: f') where
	g'ds'Shape (L1 f)  = g'ds'Shape f
   g'ds'Shape (R1 f') = g'ds'Shape f'

instance DataSource a ⇒ GDataSourceAcq (K1 i (a DSAcq)) where
	g'ds'Shape (K1 acq) = ds'Shape acq

instance GDataSourceAcq (K1 i Dataset) where
    g'ds'Shape (K1 ds) = liftIO $ ds'Shape'Dataset ds

instance GDataSourceAcq (K1 R Degree) where
    g'ds'Shape _ = pure shape1

instance GDataSourceAcq (K1 R Double) where
    g'ds'Shape _ = pure shape1

instance GDataSourceAcq (K1 R Geometry) where
    g'ds'Shape _ = pure shape1

instance GDataSourceAcq (K1 R (Text → Scannumber → Int → FilePath)) where
    g'ds'Shape _ = pure shape1

instance GDataSourceAcq (K1 R (Detector Hkl DIM2)) where
    g'ds'Shape _ = pure shape1

instance GDataSourceAcq (K1 R (IOVector a)) where
    g'ds'Shape _ = pure shape1

instance GDataSourceAcq (K1 R Text) where
    g'ds'Shape _ = pure shape1

instance GDataSourceAcq (K1 R Scannumber) where
    g'ds'Shape _ = pure shape1

Re: [Haskell-cafe] Is there a way to make this code compose generic ?

PICCA Frederic-Emmanuel