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

9 Apr 2025


      Another question related to this one
...
data ExampleData
...
instance DataSource ExampleData where
  data DataSourceT k ExampleData = DataSource'ExampleData
    (DataSourceT k BaseData)
    (DataSourceT k BaseData)
    (DataSourceT k BaseData)
    (DataSourceT k BaseData)
    (DataSourceT k BaseData)
    deriving Generic
  ds'Shape = generic'ds'Shape
  withDataSourceP = generic'withDataSourceP
Do you think that it is possible to derive the

DataSourceT Acq and Path from the ExampleData type


data ExampleData = ExampleData A B

it seems mechanical to me

data DataSourceT k ExampleDAta
  = DataSource'ExampleData
    (DataSourceT k A)
    (DataSourceT k B)

I tryed with HKD like this

-- "Higher-Kinded Data"                                                                                                                    
type family HKD f a where
  HKD Identity a = a
  HKD f        a = f a         

data ExampleData' f
  = ExampleData
   (HKD f A)
   (HKD f B)

where

but then I do not know howto define the type family for DataSourceT with this ExampleData' f

Cheers

Fred

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

PICCA Frederic-Emmanuel