refactor(users/glittershark): Rename to grfn r/2485

Rename my //users directory and all places that refer to glittershark to
grfn, including nix references and documentation.

This may require some extra attention inside of gerrit's database after
it lands to allow me to actually push things.

Change-Id: I4728b7ec2c60024392c1c1fa6e0d4a59b3e266fa
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2933
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
Reviewed-by: lukegb <lukegb@tvl.fyi>
Reviewed-by: glittershark <grfn@gws.fyi>

1 files changed, 167 insertions, 0 deletions

diff --git a/users/grfn/xanthous/src/Data/Aeson/Generic/DerivingVia.hs b/users/grfn/xanthous/src/Data/Aeson/Generic/DerivingVia.hs
new file mode 100644
index 000000000000..34f2a9403892
--- /dev/null
+++ b/users/grfn/xanthous/src/Data/Aeson/Generic/DerivingVia.hs
@@ -0,0 +1,167 @@
+{-# LANGUAGE ConstraintKinds, DataKinds, DeriveGeneric, DerivingVia    #-}
+{-# LANGUAGE ExplicitNamespaces, FlexibleContexts, FlexibleInstances   #-}
+{-# LANGUAGE GADTs, GeneralizedNewtypeDeriving, MultiParamTypeClasses  #-}
+{-# LANGUAGE PolyKinds, ScopedTypeVariables, StandaloneDeriving        #-}
+{-# LANGUAGE TypeApplications, TypeFamilies, TypeInType, TypeOperators #-}
+{-# LANGUAGE UndecidableInstances                                      #-}
+{-# OPTIONS_GHC -Wall #-}
+-- | https://gist.github.com/konn/27c00f784dd883ec2b90eab8bc84a81d
+module Data.Aeson.Generic.DerivingVia
+     ( StrFun(..), Setting(..), SumEncoding'(..), DefaultOptions, WithOptions(..)
+     , -- Utility type synonyms to save ticks (') before promoted data constructors
+       type Drop, type CamelTo2, type UserDefined
+     , type TaggedObj, type UntaggedVal, type ObjWithSingleField, type TwoElemArr
+     , type FieldLabelModifier
+     , type ConstructorTagModifier
+     , type AllNullaryToStringTag
+     , type OmitNothingFields
+     , type SumEnc
+     , type UnwrapUnaryRecords
+     , type TagSingleConstructors
+     )
+  where
+
+import           Prelude
+import           Data.Aeson      (FromJSON (..), GFromJSON, GToJSON,
+                                  ToJSON (..))
+import           Data.Aeson      (Options (..), Zero, camelTo2,
+                                  genericParseJSON)
+import           Data.Aeson      (defaultOptions, genericToJSON)
+import qualified Data.Aeson      as Aeson
+import           Data.Kind       (Constraint, Type)
+import           Data.Proxy      (Proxy (..))
+import           Data.Reflection (Reifies (..))
+import           GHC.Generics    (Generic, Rep)
+import           GHC.TypeLits    (KnownNat, KnownSymbol, natVal, symbolVal)
+import           GHC.TypeLits    (Nat, Symbol)
+
+newtype WithOptions options a = WithOptions { runWithOptions :: a }
+
+data StrFun = Drop     Nat
+            | CamelTo2 Symbol
+            | forall p. UserDefined p
+
+type Drop = 'Drop
+type CamelTo2 = 'CamelTo2
+type UserDefined = 'UserDefined
+
+type family Demoted a where
+  Demoted Symbol  = String
+  Demoted StrFun  = String -> String
+  Demoted [a]     = [Demoted a]
+  Demoted Setting = Options -> Options
+  Demoted SumEncoding' = Aeson.SumEncoding
+  Demoted a = a
+
+data SumEncoding' = TaggedObj {tagFieldName' :: Symbol, contentsFieldName :: Symbol }
+                  | UntaggedVal
+                  | ObjWithSingleField
+                  | TwoElemArr
+
+type TaggedObj          = 'TaggedObj
+type UntaggedVal        = 'UntaggedVal
+type ObjWithSingleField = 'ObjWithSingleField
+type TwoElemArr         = 'TwoElemArr
+
+data Setting = FieldLabelModifier     [StrFun]
+             | ConstructorTagModifier [StrFun]
+             | AllNullaryToStringTag  Bool
+             | OmitNothingFields      Bool
+             | SumEnc                 SumEncoding'
+             | UnwrapUnaryRecords     Bool
+             | TagSingleConstructors  Bool
+
+type FieldLabelModifier     = 'FieldLabelModifier
+type ConstructorTagModifier = 'ConstructorTagModifier
+-- | If 'True' the constructors of a datatype, with all nullary constructors,
+-- will be encoded to just a string with the constructor tag. If 'False' the
+-- encoding will always follow the 'SumEncoding'.
+type AllNullaryToStringTag  = 'AllNullaryToStringTag
+type OmitNothingFields      = 'OmitNothingFields
+type SumEnc                 = 'SumEnc
+-- | Hide the field name when a record constructor has only one field, like a
+-- newtype.
+type UnwrapUnaryRecords     = 'UnwrapUnaryRecords
+-- | Encode types with a single constructor as sums, so that
+-- 'AllNullaryToStringTag' and 'SumEncoding' apply.
+type TagSingleConstructors  = 'TagSingleConstructors
+
+class Demotable (a :: k) where
+  demote :: proxy a -> Demoted k
+
+type family All (p :: Type -> Constraint) (xs :: [k]) :: Constraint where
+  All p '[] = ()
+  All p (x ': xs) = (p x, All p xs)
+
+instance Reifies f (String -> String) => Demotable ('UserDefined f) where
+  demote _ = reflect @f Proxy
+
+instance KnownSymbol sym => Demotable sym where
+  demote = symbolVal
+
+instance (KnownSymbol s, KnownSymbol t) => Demotable ('TaggedObj s t) where
+  demote _ = Aeson.TaggedObject (symbolVal @s Proxy) (symbolVal @t Proxy)
+
+instance Demotable 'UntaggedVal where
+  demote _ = Aeson.UntaggedValue
+
+instance Demotable 'ObjWithSingleField where
+  demote _ = Aeson.ObjectWithSingleField
+
+instance Demotable 'TwoElemArr where
+  demote _ = Aeson.TwoElemArray
+
+instance Demotable xs => Demotable ('FieldLabelModifier xs) where
+  demote _ o = o { fieldLabelModifier = foldr (.) id (demote (Proxy @xs)) }
+
+instance Demotable xs => Demotable ('ConstructorTagModifier xs) where
+  demote _ o = o { constructorTagModifier = foldr (.) id (demote (Proxy @xs)) }
+
+instance Demotable b => Demotable ('AllNullaryToStringTag b) where
+  demote _ o = o { allNullaryToStringTag = demote (Proxy @b) }
+
+instance Demotable b => Demotable ('OmitNothingFields b) where
+  demote _ o = o { omitNothingFields = demote (Proxy @b) }
+
+instance Demotable b => Demotable ('UnwrapUnaryRecords b) where
+  demote _ o = o { unwrapUnaryRecords = demote (Proxy @b) }
+
+instance Demotable b => Demotable ('TagSingleConstructors b) where
+  demote _ o = o { tagSingleConstructors = demote (Proxy @b) }
+
+instance Demotable b => Demotable ('SumEnc b) where
+  demote _ o = o { sumEncoding = demote (Proxy @b) }
+
+instance Demotable 'True where
+  demote _ = True
+
+instance Demotable 'False where
+  demote _ = False
+
+instance KnownNat n => Demotable ('Drop n) where
+  demote _ = drop (fromIntegral $ natVal (Proxy :: Proxy n))
+
+instance KnownSymbol sym => Demotable ('CamelTo2 sym) where
+  demote _ = camelTo2 $ head $ symbolVal @sym Proxy
+
+instance {-# OVERLAPPING #-} Demotable ('[] :: [k]) where
+  demote _ = []
+
+instance (Demotable (x :: k), Demotable (xs :: [k])) => Demotable (x ': xs) where
+  demote _ = demote (Proxy @x) : demote (Proxy @xs)
+
+type DefaultOptions = ('[] :: [Setting])
+
+reflectOptions :: forall xs proxy. Demotable (xs :: [Setting]) => proxy xs -> Options
+reflectOptions pxy = foldr (.) id (demote pxy) defaultOptions
+
+instance (Demotable (options :: [Setting])) => Reifies options Options where
+  reflect = reflectOptions
+
+instance (Generic a, GToJSON Zero (Rep a), Reifies (options :: k) Options)
+       => ToJSON (WithOptions options a) where
+  toJSON = genericToJSON (reflect (Proxy @options)) . runWithOptions
+
+instance (Generic a, GFromJSON Zero (Rep a), Reifies (options :: k) Options)
+       => FromJSON (WithOptions options a) where
+  parseJSON = fmap WithOptions . genericParseJSON (reflect (Proxy @options))