Hi all,
(I think something went wrong with my previous email, so if this
is sent twice, I apologize)
Why do self referential structure omit the selector in record
entries referencing themselves when converting to the regular data
structure?
For instance, when splicing the following data structure:
data P = V {v::String} | II {i::Integer} | P { p::P }
deriving Show
$(deriveAll ''P "PFP")
type instance PF P = PFP
It generates the following code:
...
generics@haskell.org
data P_P_ =
...
instance Constructor P_P_ where
{ conName _ = "P"
conIsRecord _ = True }
...
data P_P_p_ =
instance Selector P_V_v_ where
{ selName _ = "v" }
...
instance Selector P_P_p_ where
{ selName _ = "p" }
type PFP = :+: (C P_V_ (S P_V_v_ (K String))) (:+: (C P_II_
(S P_II_i_ (K Integer))) (C P_P_ I))
instance Regular P where
{ ...
generics@haskell.org
from II f0 = R (L (C (S (K f0))))
from P f0 = R (R (C (I f0)))
...
to R L C S K f0 = II f0
to R R C I f0 = P f0 }
Why is the selector name in case of a self referencing record
omitted? I would have expected something like this:
type PFP = :+: (C P_V_ (S P_V_v_ (K String))) (:+: (C P_II_
(S P_II_i_ (K Integer))) (C P_P_ (S P_P_p_ I)))
and likewise:
from II f0 = R (L (C (S (K f0))))
from P f0 = R (R (C (S (I f0))))
...
to R L C S K f0 = II f0
to R R C S I f0 = P f0 }
This gives problems when parsing these kind of structure, or am I
missing something?
kind regards,
Maarten