{-# LANGUAGE TypeApplications #-}

{-# OPTIONS_GHC -Wwarn #-}

module Data.Record.Generic.Eq (
    geq
  , gcompare
  ) where

import Data.Record.Generic
import qualified Data.Record.Generic.Rep as Rep

-- | Generic equality function
--
-- Typical usage:
--
-- > instance Eq T where
-- >   (==) = geq
--
-- TODO: Should we worry about short-circuiting here?
geq :: (Generic a, Constraints a Eq) => a -> a -> Bool
geq :: forall a. (Generic a, Constraints a Eq) => a -> a -> Bool
geq = \a
x a
y ->
      forall (t :: * -> *). Foldable t => t Bool -> Bool
and
    forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. Rep (K a) b -> [a]
Rep.collapse
    forall a b. (a -> b) -> a -> b
$ forall a (c :: * -> Constraint) (f :: * -> *) (g :: * -> *)
       (h :: * -> *).
(Generic a, Constraints a c) =>
Proxy c
-> (forall x. c x => f x -> g x -> h x)
-> Rep f a
-> Rep g a
-> Rep h a
Rep.czipWith (forall {k} (t :: k). Proxy t
Proxy @Eq) forall x. Eq x => I x -> I x -> K Bool x
compareField (forall a. Generic a => a -> Rep I a
from a
x) (forall a. Generic a => a -> Rep I a
from a
y)
  where
    compareField :: Eq x => I x -> I x -> K Bool x
    compareField :: forall x. Eq x => I x -> I x -> K Bool x
compareField (I x
x) (I x
y) = forall k a (b :: k). a -> K a b
K (x
x forall a. Eq a => a -> a -> Bool
== x
y)

gcompare :: (Generic a, Constraints a Ord) => a -> a -> Ordering
gcompare :: forall a. (Generic a, Constraints a Ord) => a -> a -> Ordering
gcompare = \a
x a
y ->
      forall a. Monoid a => [a] -> a
mconcat
    forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. Rep (K a) b -> [a]
Rep.collapse
    forall a b. (a -> b) -> a -> b
$ forall a (c :: * -> Constraint) (f :: * -> *) (g :: * -> *)
       (h :: * -> *).
(Generic a, Constraints a c) =>
Proxy c
-> (forall x. c x => f x -> g x -> h x)
-> Rep f a
-> Rep g a
-> Rep h a
Rep.czipWith (forall {k} (t :: k). Proxy t
Proxy @Ord) forall x. Ord x => I x -> I x -> K Ordering x
compareField (forall a. Generic a => a -> Rep I a
from a
x) (forall a. Generic a => a -> Rep I a
from a
y)
  where
    compareField :: Ord x => I x -> I x -> K Ordering x
    compareField :: forall x. Ord x => I x -> I x -> K Ordering x
compareField (I x
x) (I x
y) = forall k a (b :: k). a -> K a b
K (forall a. Ord a => a -> a -> Ordering
compare x
x x
y)