{-|
A convenience class for retrieving the first field of any constructor in a
datatype.

The primary usage for this class is generic derivation:

    data D a = D a () String deriving Generic
    instance SecondParameter (D a) ()

Note that _the deriver does not check you are requesting a valid/safe instance._
Invalid instances propagate the error to runtime. Fixing this requires a lot
more type-level work. (The generic-lens library has a general solution, but it's
slow and memory-consuming.)
-}

{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE FunctionalDependencies #-}

module Language.Fortran.Util.SecondParameter(SecondParameter(..)) where

import GHC.Generics

class SecondParameter a e | a -> e where
  getSecondParameter :: a -> e
  setSecondParameter :: e -> a -> a

  default getSecondParameter :: (Generic a, GSecondParameter (Rep a) e) => a -> e
  getSecondParameter = forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
f a -> e
getSecondParameter' forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a x. Generic a => a -> Rep a x
from

  default setSecondParameter :: (Generic a, GSecondParameter (Rep a) e) => e -> a -> a
  setSecondParameter e
e = forall a x. Generic a => Rep a x -> a
to forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
e -> f a -> f a
setSecondParameter' e
e forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a x. Generic a => a -> Rep a x
from

class GSecondParameter f e where
  getSecondParameter' :: f a -> e
  setSecondParameter' :: e -> f a -> f a

instance GSecondParameter (K1 i a) e where
  getSecondParameter' :: forall (a :: k). K1 i a a -> e
getSecondParameter' K1 i a a
_ = forall a. HasCallStack => a
undefined
  setSecondParameter' :: forall (a :: k). e -> K1 i a a -> K1 i a a
setSecondParameter' e
_ = forall a. HasCallStack => a
undefined

instance GSecondParameter a e => GSecondParameter (M1 i c a) e where
  getSecondParameter' :: forall (a :: k). M1 i c a a -> e
getSecondParameter' (M1 a a
x) = forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
f a -> e
getSecondParameter' a a
x
  setSecondParameter' :: forall (a :: k). e -> M1 i c a a -> M1 i c a a
setSecondParameter' e
e (M1 a a
x) = forall k i (c :: Meta) (f :: k -> *) (p :: k). f p -> M1 i c f p
M1 forall a b. (a -> b) -> a -> b
$ forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
e -> f a -> f a
setSecondParameter' e
e a a
x

instance (GSecondParameter a e, GSecondParameter b e) => GSecondParameter (a :+: b) e where
  getSecondParameter' :: forall (a :: k). (:+:) a b a -> e
getSecondParameter' (L1 a a
a) = forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
f a -> e
getSecondParameter' a a
a
  getSecondParameter' (R1 b a
a) = forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
f a -> e
getSecondParameter' b a
a

  setSecondParameter' :: forall (a :: k). e -> (:+:) a b a -> (:+:) a b a
setSecondParameter' e
e (L1 a a
a) = forall k (f :: k -> *) (g :: k -> *) (p :: k). f p -> (:+:) f g p
L1 forall a b. (a -> b) -> a -> b
$ forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
e -> f a -> f a
setSecondParameter' e
e a a
a
  setSecondParameter' e
e (R1 b a
a) = forall k (f :: k -> *) (g :: k -> *) (p :: k). g p -> (:+:) f g p
R1 forall a b. (a -> b) -> a -> b
$ forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
e -> f a -> f a
setSecondParameter' e
e b a
a

instance (ParameterLeaf a, GSecondParameter a e, GSecondParameter' b e) => GSecondParameter (a :*: b) e where
  getSecondParameter' :: forall (a :: k). (:*:) a b a -> e
getSecondParameter' (a a
a :*: b a
b) = 
    if forall {k} (f :: k -> *) (a :: k). ParameterLeaf f => f a -> Bool
isLeaf a a
a 
    then forall {k} (f :: k -> *) e (a :: k).
GSecondParameter' f e =>
f a -> e
getSecondParameter'' b a
b
    else forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
f a -> e
getSecondParameter' a a
a

  setSecondParameter' :: forall (a :: k). e -> (:*:) a b a -> (:*:) a b a
setSecondParameter' e
e (a a
a :*: b a
b) = 
    if forall {k} (f :: k -> *) (a :: k). ParameterLeaf f => f a -> Bool
isLeaf a a
a 
    then a a
a forall k (f :: k -> *) (g :: k -> *) (p :: k).
f p -> g p -> (:*:) f g p
:*: forall {k} (f :: k -> *) e (a :: k).
GSecondParameter' f e =>
e -> f a -> f a
setSecondParameter'' e
e b a
b
    else forall {k} (f :: k -> *) e (a :: k).
GSecondParameter f e =>
e -> f a -> f a
setSecondParameter' e
e a a
a forall k (f :: k -> *) (g :: k -> *) (p :: k).
f p -> g p -> (:*:) f g p
:*: b a
b

class GSecondParameter' f e where
  getSecondParameter'' :: f a -> e
  setSecondParameter'' :: e -> f a -> f a

instance GSecondParameter' a e => GSecondParameter' (M1 i c a) e where
  getSecondParameter'' :: forall (a :: k). M1 i c a a -> e
getSecondParameter'' (M1 a a
a) = forall {k} (f :: k -> *) e (a :: k).
GSecondParameter' f e =>
f a -> e
getSecondParameter'' a a
a
  setSecondParameter'' :: forall (a :: k). e -> M1 i c a a -> M1 i c a a
setSecondParameter'' e
e (M1 a a
a) = forall k i (c :: Meta) (f :: k -> *) (p :: k). f p -> M1 i c f p
M1 forall a b. (a -> b) -> a -> b
$ forall {k} (f :: k -> *) e (a :: k).
GSecondParameter' f e =>
e -> f a -> f a
setSecondParameter'' e
e a a
a

instance GSecondParameter' a e => GSecondParameter' (a :*: b) e where
  getSecondParameter'' :: forall (a :: k). (:*:) a b a -> e
getSecondParameter'' (a a
a :*: b a
_) = forall {k} (f :: k -> *) e (a :: k).
GSecondParameter' f e =>
f a -> e
getSecondParameter'' a a
a
  setSecondParameter'' :: forall (a :: k). e -> (:*:) a b a -> (:*:) a b a
setSecondParameter'' e
e (a a
a :*: b a
b) = forall {k} (f :: k -> *) e (a :: k).
GSecondParameter' f e =>
e -> f a -> f a
setSecondParameter'' e
e a a
a forall k (f :: k -> *) (g :: k -> *) (p :: k).
f p -> g p -> (:*:) f g p
:*: b a
b

instance {-# OVERLAPPING #-} GSecondParameter' (K1 i e) e where
  getSecondParameter'' :: forall (a :: k). K1 i e a -> e
getSecondParameter'' (K1 e
a) = e
a
  setSecondParameter'' :: forall (a :: k). e -> K1 i e a -> K1 i e a
setSecondParameter'' e
e (K1 e
_) = forall k i c (p :: k). c -> K1 i c p
K1 e
e

instance {-# OVERLAPPABLE #-} GSecondParameter' (K1 i a) e where
  getSecondParameter'' :: forall (a :: k). K1 i a a -> e
getSecondParameter'' K1 i a a
_ = forall a. HasCallStack => a
undefined
  setSecondParameter'' :: forall (a :: k). e -> K1 i a a -> K1 i a a
setSecondParameter'' e
_ K1 i a a
_  = forall a. HasCallStack => a
undefined

class ParameterLeaf f where
  isLeaf :: f a -> Bool

instance ParameterLeaf (M1 i c a) where
  isLeaf :: forall (a :: k). M1 i c a a -> Bool
isLeaf M1 i c a a
_ = Bool
True

instance ParameterLeaf (a :*: b) where
  isLeaf :: forall (a :: k). (:*:) a b a -> Bool
isLeaf (:*:) a b a
_ = Bool
False