Optparse-Generic-Like это кстати вообще легко делается newtype t <?> n =

Question

Optparse-Generic-Like это кстати вообще легко делается newtype t <?> n =

N t
deriving stock Show

type family MapFields x where
MapFields (S1 ('MetaSel _ a b c) (Rec0 (t <?> n))) = S1 ('MetaSel ('Just n) a b c) (Rec0 t)
MapFields (M1 i meta cs) = M1 i meta (MapFields cs)
MapFields (a :+: b) = MapFields a :+: MapFields b
MapFields (a :*: b) = MapFields a :*: MapFields b
MapFields other = other

newtype ViaNamed a = ViaNamed a
deriving anyclass instance (Generic (ViaNamed a), GFromJSON Zero (Rep (ViaNamed a))) => FromJSON (ViaNamed a)
deriving anyclass instance (Generic (ViaNamed a), GToJSON Zero (Rep (ViaNamed a))) => ToJSON (ViaNamed a)

instance (Generic a, Coercible (Rep a) (Rep (ViaNamed a))) => Generic (ViaNamed a) where
type Rep (ViaNamed a) = MapFields (Rep a)
from :: forall x . ViaNamed a -> Rep (ViaNamed a) x
from = coerce $ from @a @x
to :: forall x . Rep (ViaNamed a) x -> ViaNamed a
to = coerce $ to @a @x

data X = X { a :: Int <?> "b" , c :: Int <?> "d" }
deriving stock (Generic, Show)
deriving (FromJSON, ToJSON) via ViaNamed X

#haskell #programming #russian

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05.07.2021

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кана · Accepted Answer

кана

тут есть существенный недостаток

0

05.07.2021

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Optparse-Generic-Like это кстати вообще легко делается newtype t <?> n =

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