haskell-to-elm-0.3.2.0: src/Language/Haskell/To/Elm.hs
{-# language AllowAmbiguousTypes #-}
{-# language DataKinds #-}
{-# language DefaultSignatures #-}
{-# language DuplicateRecordFields #-}
{-# language FlexibleContexts #-}
{-# language FlexibleInstances #-}
{-# language GADTs #-}
{-# language MultiParamTypeClasses #-}
{-# language OverloadedStrings #-}
{-# language PartialTypeSignatures #-}
{-# language PolyKinds #-}
{-# language ScopedTypeVariables #-}
{-# language TypeApplications #-}
{-# language TypeOperators #-}
{-# language UndecidableInstances #-}
module Language.Haskell.To.Elm where
import qualified Bound
import qualified Data.Aeson as Aeson
import Data.Bifunctor (first, second)
import Data.Foldable
import Data.HashMap.Lazy (HashMap)
import qualified Data.HashMap.Lazy as HashMap
import qualified Data.Int as Int
import qualified Data.Kind
import Data.Maybe (catMaybes)
import Data.Proxy
import Data.String
import Data.Text (Text)
import Data.Time
import Data.Vector (Vector)
import Data.Void
import qualified Data.Word as Word
import qualified Generics.SOP as SOP
import GHC.TypeLits
import Language.Elm.Definition (Definition)
import qualified Language.Elm.Definition as Definition
import Language.Elm.Expression (Expression)
import qualified Language.Elm.Expression as Expression
import qualified Language.Elm.Name as Name
import qualified Language.Elm.Pattern as Pattern
import Language.Elm.Type (Type)
import qualified Language.Elm.Type as Type
import Language.Haskell.To.Elm.DataShape
-------------------------------------------------------------------------------
-- * Classes
-- | Represents that the corresponding Elm type for the Haskell type @a@ is @'elmType' \@a@.
class HasElmType a where
elmType :: Type v
default elmType :: Type v
elmType =
Type.Global $
maybe
(error "default-implemented 'elmType' without a definition")
Definition.name $
elmDefinition @a
-- | When 'Just', this represents that we can generate the definition for the
-- Elm type that corresponds to @a@ using @'elmDefinition' \@a@.
--
-- See 'deriveElmTypeDefinition' for a way to automatically derive 'elmDefinition'.
--
-- When 'Nothing', it means that the type is an already existing Elm type
-- that does not need to be generated.
elmDefinition :: Maybe Definition
elmDefinition =
Nothing
{-# minimal elmType | elmDefinition #-}
-- | Represents that the Elm type that corresponds to @a@ has a decoder from
-- @value@, namely @'elmDecoder' \@value \@a@.
class HasElmType a => HasElmDecoder value a where
elmDecoder :: Expression v
default elmDecoder :: Expression v
elmDecoder =
Expression.Global $
maybe
(error "default-implemented 'elmDecoder' without a definition")
Definition.name $
elmDecoderDefinition @value @a
-- | When 'Just', this represents that we can generate the Elm decoder definition
-- from @value@ for the Elm type that corresponds to @a@.
--
-- See 'deriveElmJSONDecoder' for a way to automatically derive
-- 'elmDecoderDefinition' when @value = 'Aeson.Value'@.
elmDecoderDefinition :: Maybe Definition
elmDecoderDefinition =
Nothing
{-# minimal elmDecoder | elmDecoderDefinition #-}
-- | Represents that the Elm type that corresponds to @a@ has an encoder into
-- @value@, namely @'elmEncoder' \@value \@a@.
--
-- This class has a default instance for types that satisfy
-- 'HasElmEncoderDefinition', which refers to the name of that definition.
class HasElmType a => HasElmEncoder value a where
elmEncoder :: Expression v
default elmEncoder :: Expression v
elmEncoder =
Expression.Global $
maybe
(error "default-implemented 'elmEncoder' without a definition")
Definition.name $
elmEncoderDefinition @value @a
-- | When 'Just', this represents that we can generate the Elm encoder
-- definition into @value@ for the Elm type that corresponds to @a@.
--
-- See 'deriveElmJSONEncoder' for a way to automatically derive
-- 'elmEncoderDefinition' when @value = 'Aeson.Value'@.
elmEncoderDefinition :: Maybe Definition
elmEncoderDefinition =
Nothing
{-# minimal elmEncoder | elmEncoderDefinition #-}
-------------------------------------------------------------------------------
-- * Derivers
-- | Elm code generation options
newtype Options = Options
{ fieldLabelModifier :: String -> String -- ^ Use this function to go from Haskell record field name to Elm record field name.
}
defaultOptions :: Options
defaultOptions =
Options
{ fieldLabelModifier = id
}
-- ** Type definitions
-- | Automatically create an Elm definition given a Haskell type.
--
-- This is suitable for use as the 'elmDefinition' in a 'HasElmType' instance:
--
-- @
-- instance 'HasElmType' MyType where
-- 'elmDefinition' =
-- 'Just' $ 'deriveElmTypeDefinition' \@MyType 'defaultOptions' \"Api.MyType.MyType\"
-- @
deriveElmTypeDefinition
:: forall a
. DeriveParameterisedElmTypeDefinition 0 a
=> Options
-> Name.Qualified
-> Definition
deriveElmTypeDefinition =
deriveParameterisedElmTypeDefinition @0 @a
class DeriveParameterisedElmTypeDefinition numParams a where
deriveParameterisedElmTypeDefinition :: Options -> Name.Qualified -> Definition
data Parameter (n :: Nat)
parameterName :: Int -> Name.Qualified
parameterName i =
Name.Qualified ["Haskell", "To", "Elm"] ("Parameter" <> fromString (show i))
instance KnownNat n => HasElmType (Parameter n) where
elmType =
Type.Global $ parameterName $ fromIntegral $ natVal $ Proxy @n
instance (DeriveParameterisedElmTypeDefinition (numParams + 1) (f (Parameter numParams))) => DeriveParameterisedElmTypeDefinition numParams (f :: Data.Kind.Type -> b) where
deriveParameterisedElmTypeDefinition =
deriveParameterisedElmTypeDefinition @(numParams + 1) @(f (Parameter numParams))
instance (KnownNat numParams, SOP.HasDatatypeInfo a, SOP.All2 HasElmType (SOP.Code a)) => DeriveParameterisedElmTypeDefinition numParams (a :: Data.Kind.Type) where
deriveParameterisedElmTypeDefinition options name =
case dataShape @a $ ConstraintFun constraintFun of
[(_cname, RecordConstructorShape fields)] ->
Definition.Alias name numParams (bindTypeParameters $ Type.Record $ first fieldName <$> fields)
cs ->
Definition.Type name numParams (fmap (fmap bindTypeParameters) <$> map (uncurry constructor) cs)
where
constraintFun :: forall v t. Dict (HasElmType t) -> Type v
constraintFun Dict =
elmType @t
typeParameterMap :: HashMap Name.Qualified Int
typeParameterMap =
HashMap.fromList [(parameterName i, i) | i <- [0..numParams - 1]]
bindTypeParameters
:: Type v
-> Bound.Scope Int Type v
bindTypeParameters =
Bound.Scope .
Type.bind
(\n -> maybe (Type.Global n) (pure . Bound.B) (HashMap.lookup n typeParameterMap))
(pure . pure . pure)
numParams =
fromIntegral $ natVal $ Proxy @numParams
constructor :: String -> ConstructorShape (Type v) -> (Name.Constructor, [Type v])
constructor cname shape =
( fromString cname
, case shape of
ConstructorShape fields ->
fields
RecordConstructorShape fs ->
[Type.Record $ first fieldName <$> fs]
)
fieldName :: String -> Name.Field
fieldName =
fromString . fieldLabelModifier options
-- ** JSON decoders
-- | Automatically create an Elm JSON decoder definition given a Haskell type.
--
-- This is suitable for use as the 'elmDecoderDefinition' in a
-- @'HasElmDecoder' 'Aeson.Value'@ instance:
--
-- @
-- instance 'HasElmDecoder' 'Aeson.Value' MyType where
-- 'elmDecoderDefinition' =
-- Just $ 'deriveElmJSONDecoder' \@MyType 'defaultOptions' 'Aeson.defaultOptions' "Api.MyType.decoder"
-- @
--
-- Uses the given 'Aeson.Options' to match the JSON format of derived
-- 'Aeson.FromJSON' and 'Aeson.ToJSON' instances.
deriveElmJSONDecoder
:: forall a
. DeriveParameterisedElmDecoderDefinition 0 Aeson.Value a
=> Options
-> Aeson.Options
-> Name.Qualified
-> Definition
deriveElmJSONDecoder =
deriveParameterisedElmDecoderDefinition @0 @Aeson.Value @a
class DeriveParameterisedElmDecoderDefinition numParams value a where
deriveParameterisedElmDecoderDefinition :: Options -> Aeson.Options -> Name.Qualified -> Definition
instance KnownNat n => HasElmDecoder value (Parameter n) where
elmDecoder =
Expression.Global $
parameterName $ fromIntegral $ natVal $ Proxy @n
instance (DeriveParameterisedElmDecoderDefinition (numParams + 1) value (f (Parameter numParams))) => DeriveParameterisedElmDecoderDefinition numParams value (f :: Data.Kind.Type -> b) where
deriveParameterisedElmDecoderDefinition =
deriveParameterisedElmDecoderDefinition @(numParams + 1) @value @(f (Parameter numParams))
instance (HasElmType a, KnownNat numParams, SOP.HasDatatypeInfo a, SOP.All2 (HasElmDecoder Aeson.Value) (SOP.Code a))
=> DeriveParameterisedElmDecoderDefinition numParams Aeson.Value (a :: Data.Kind.Type) where
deriveParameterisedElmDecoderDefinition options aesonOptions decoderName =
Definition.Constant decoderName numParams parameterisedType $
parameteriseBody $
case dataShape @a $ ConstraintFun constraintFun of
[(_cname, RecordConstructorShape fields)] ->
decodeRecordFields fields $
Expression.App "Json.Decode.succeed" $
case Type.appsView (elmType @a) of
(Type.Record fieldTypes, _) ->
explicitRecordConstructor $ fst <$> fieldTypes
_ ->
Expression.Global typeName
cs ->
decodeConstructors cs
where
constraintFun :: forall v t. Dict (HasElmDecoder Aeson.Value t) -> (Type Void, Expression v)
constraintFun Dict =
(elmType @t, elmDecoder @Aeson.Value @t)
numParams =
fromIntegral $ natVal $ Proxy @numParams
parameterisedType :: Bound.Scope Int Type v
parameterisedType =
foldr
(\i (Bound.Scope rest) ->
Bound.Scope $ Type.Fun (Type.App "Json.Decode.Decoder" $ pure $ Bound.B i) rest
)
(Bound.Scope $ Type.App "Json.Decode.Decoder" $ bindTypeParameters $ elmType @a)
[0..numParams - 1]
typeParameterMap :: HashMap Name.Qualified Int
typeParameterMap =
HashMap.fromList [(parameterName i, i) | i <- [0..numParams - 1]]
bindTypeParameters :: Type v -> Type (Bound.Var Int v)
bindTypeParameters =
Type.bind
(\n -> maybe (Type.Global n) (pure . Bound.B) (HashMap.lookup n typeParameterMap))
(pure . pure)
parameteriseBody :: Expression v -> Expression v
parameteriseBody body =
foldr
(\i ->
Expression.Lam .
Bound.toScope .
Expression.bind
(\global ->
if global == parameterName i then
pure $ Bound.B ()
else
Expression.Global global
)
(pure . pure)
)
body
[0..numParams - 1]
typeName@(Name.Qualified moduleName_ _) =
case Type.appsView (elmType @a) of
(Type.Global tname, _) -> tname
_ ->
error "Can't automatically derive JSON decoder for an anonymous Elm type"
explicitRecordConstructor :: [Name.Field] -> Expression v
explicitRecordConstructor names =
go mempty names
where
go :: HashMap Name.Field v -> [Name.Field] -> Expression v
go locals fnames =
case fnames of
[] ->
Expression.Record [(name, Expression.Var $ locals HashMap.! name) | name <- names]
fname:fnames' ->
Expression.Lam $ Bound.toScope $ go (HashMap.insert fname (Bound.B ()) $ Bound.F <$> locals) fnames'
decodeRecordFields :: [(String, (Type Void, Expression v))] -> Expression v -> Expression v
decodeRecordFields [(_, (_, decoder))] e
| Aeson.unwrapUnaryRecords aesonOptions =
e Expression.|> decoder
decodeRecordFields fs e =
foldl' (Expression.|>) e $ decodeRecordField <$> fs
decodeRecordField :: (String, (Type Void, Expression v)) -> Expression v
decodeRecordField (fname, (type_, decoder))
| Aeson.omitNothingFields aesonOptions
, (Type.Global "Maybe.Maybe", _) <- Type.appsView type_ =
Expression.apps
"Json.Decode.Pipeline.optional"
[ jsonFieldName fname
, decoder
, "Maybe.Nothing"
]
| otherwise =
Expression.apps
"Json.Decode.Pipeline.required"
[ jsonFieldName fname
, decoder
]
constructorJSONName :: String -> Text
constructorJSONName = fromString . Aeson.constructorTagModifier aesonOptions
jsonFieldName :: String -> Expression v
jsonFieldName = Expression.String . fromString . Aeson.fieldLabelModifier aesonOptions
elmField :: String -> Name.Field
elmField = fromString . fieldLabelModifier options
decodeConstructor :: String -> Expression v -> ConstructorShape (Type Void, Expression v) -> Expression v
decodeConstructor _ constr (ConstructorShape []) =
Expression.App "Json.Decode.succeed" constr
decodeConstructor contentsName constr (ConstructorShape [(_, fieldDecoder)]) =
Expression.App "Json.Decode.succeed" constr Expression.|>
Expression.apps "Json.Decode.Pipeline.required" [Expression.String (fromString contentsName), fieldDecoder]
decodeConstructor contentsName constr (ConstructorShape fields) =
Expression.apps
"Json.Decode.field"
[ Expression.String (fromString contentsName)
, foldl'
(Expression.|>)
(Expression.App "Json.Decode.succeed" constr)
[ Expression.App
"Json.Decode.Pipeline.custom"
(Expression.apps "Json.Decode.index" [Expression.Int index, fieldDecoder])
| (index, (_, fieldDecoder)) <- zip [0..] fields
]
]
decodeConstructor _contentsName constr (RecordConstructorShape fields) =
Expression.apps "Json.Decode.map"
[ constr
, decodeRecordFields fields $
Expression.App "Json.Decode.succeed" $
explicitRecordConstructor $ elmField . fst <$> fields
]
decodeConstructors :: [(String, ConstructorShape (Type Void, Expression v))] -> Expression v
decodeConstructors [(constr, constrShape)]
| not $ Aeson.tagSingleConstructors aesonOptions =
let
qualifiedConstr =
Expression.Global $ Name.Qualified moduleName_ $ fromString constr
in
case constrShape of
ConstructorShape [(_, fieldDecoder)] ->
Expression.apps "Json.Decode.map" [qualifiedConstr, fieldDecoder]
ConstructorShape fields ->
foldl'
(Expression.|>)
(Expression.App "Json.Decode.succeed" qualifiedConstr)
[Expression.App
"Json.Decode.Pipeline.custom"
(Expression.apps "Json.Decode.index" [Expression.Int index, fieldDecoder])
| (index, (_, fieldDecoder)) <- zip [0..] fields
]
RecordConstructorShape fields ->
Expression.apps "Json.Decode.map"
[ qualifiedConstr
, decodeRecordFields fields $
Expression.App "Json.Decode.succeed" $
explicitRecordConstructor $ elmField . fst <$> fields
]
decodeConstructors constrs
| Aeson.allNullaryToStringTag aesonOptions && all (nullary . snd) constrs =
"Json.Decode.string" Expression.|> Expression.App "Json.Decode.andThen" (Expression.Lam
(Bound.toScope $ Expression.Case (pure $ Bound.B ()) $
[ ( Pattern.String $ constructorJSONName constr
, Bound.toScope $ Expression.App "Json.Decode.succeed" qualifiedConstr
)
| (constr, _) <- constrs
, let
qualifiedConstr =
Expression.Global $ Name.Qualified moduleName_ $ fromString constr
]
++
[ ( Pattern.Wildcard
, Bound.toScope $ Expression.App "Json.Decode.fail" $ Expression.String "No matching constructor"
)
]
))
decodeConstructors constrs =
case Aeson.sumEncoding aesonOptions of
Aeson.TaggedObject tagName contentsName ->
Expression.apps "Json.Decode.field" [Expression.String $ fromString tagName, "Json.Decode.string"] Expression.|>
Expression.App "Json.Decode.andThen" (Expression.Lam
(Bound.toScope $ Expression.Case (pure $ Bound.B ()) $
[ ( Pattern.String $ constructorJSONName constr
, Bound.toScope $
decodeConstructor contentsName qualifiedConstr $
second (fmap $ Bound.F . Bound.F) <$> shape
)
| (constr, shape) <- constrs
, let
qualifiedConstr =
Expression.Global $ Name.Qualified moduleName_ $ fromString constr
]
++
[ ( Pattern.Wildcard
, Bound.toScope $ Expression.App "Json.Decode.fail" $ Expression.String "No matching constructor"
)
]
))
_ -> error "Only the DataAeson.TaggedObject sumEncoding is currently supported"
-- ** JSON encoders
-- | Automatically create an Elm JSON encoder definition given a Haskell type.
--
-- This is suitable for use as the 'elmEncoderDefinition' in a @'HasElmEncoder 'Aeson.Value'@ instance:
--
-- @
-- instance 'HasElmEncoder' 'Aeson.Value' MyType where
-- 'elmEncoderDefinition' =
-- 'Just' $ 'deriveElmJSONEncoder' \@MyType 'defaultOptions' 'Aeson.defaultOptions' "Api.MyType.encoder"
-- @
--
-- Uses the given 'Aeson.Options' to match the JSON format of derived
-- 'Aeson.FromJSON' and 'Aeson.ToJSON' instances.
deriveElmJSONEncoder
:: forall a
. DeriveParameterisedElmEncoderDefinition 0 Aeson.Value a
=> Options
-> Aeson.Options
-> Name.Qualified
-> Definition
deriveElmJSONEncoder =
deriveParameterisedElmEncoderDefinition @0 @Aeson.Value @a
class DeriveParameterisedElmEncoderDefinition numParams value a where
deriveParameterisedElmEncoderDefinition :: Options -> Aeson.Options -> Name.Qualified -> Definition
instance KnownNat n => HasElmEncoder value (Parameter n) where
elmEncoder =
Expression.Global $
parameterName $ fromIntegral $ natVal $ Proxy @n
instance (DeriveParameterisedElmEncoderDefinition (numParams + 1) value (f (Parameter numParams))) => DeriveParameterisedElmEncoderDefinition numParams value (f :: Data.Kind.Type -> b) where
deriveParameterisedElmEncoderDefinition =
deriveParameterisedElmEncoderDefinition @(numParams + 1) @value @(f (Parameter numParams))
instance (HasElmType a, KnownNat numParams, SOP.HasDatatypeInfo a, SOP.All2 (HasElmEncoder Aeson.Value) (SOP.Code a))
=> DeriveParameterisedElmEncoderDefinition numParams Aeson.Value (a :: Data.Kind.Type) where
deriveParameterisedElmEncoderDefinition options aesonOptions encoderName =
Definition.Constant encoderName numParams parameterisedType $
parameteriseBody $
Expression.Lam $ Bound.toScope $
case dataShape @a $ ConstraintFun constraintFun of
[(_cname, RecordConstructorShape fields)] ->
Expression.App "Json.Encode.object" $
encodedRecordFieldList fields $ pure $ Bound.B ()
cs ->
encodeConstructors cs (pure $ Bound.B ())
where
constraintFun :: forall v t. Dict (HasElmEncoder Aeson.Value t) -> (Type Void, Expression v)
constraintFun Dict =
(elmType @t, elmEncoder @Aeson.Value @t)
numParams =
fromIntegral $ natVal $ Proxy @numParams
parameterisedType :: Bound.Scope Int Type v
parameterisedType =
foldr
(\i (Bound.Scope rest) ->
Bound.Scope $ Type.Fun (Type.Fun (pure $ Bound.B i) "Json.Encode.Value") rest
)
(Bound.Scope $ Type.Fun (bindTypeParameters $ elmType @a) "Json.Encode.Value")
[0..numParams - 1]
typeParameterMap :: HashMap Name.Qualified Int
typeParameterMap =
HashMap.fromList [(parameterName i, i) | i <- [0..numParams - 1]]
bindTypeParameters :: Type v -> Type (Bound.Var Int v)
bindTypeParameters =
Type.bind
(\n -> maybe (Type.Global n) (pure . Bound.B) (HashMap.lookup n typeParameterMap))
(pure . pure)
parameteriseBody :: Expression v -> Expression v
parameteriseBody body =
foldr
(\i ->
Expression.Lam .
Bound.toScope .
Expression.bind
(\global ->
if global == parameterName i then
pure $ Bound.B ()
else
Expression.Global global
)
(pure . pure)
)
body
[0..numParams - 1]
(Name.Qualified moduleName_ _) =
case Type.appsView (elmType @a) of
(Type.Global tname, _) -> tname
_ ->
error "Can't automatically derive JSON encoder for an anonymous Elm type"
encodedRecordFieldList :: [(String, (Type Void, Expression v))] -> Expression v -> Expression v
encodedRecordFieldList [(_, (_, encoder))] e
| Aeson.unwrapUnaryRecords aesonOptions =
Expression.App encoder e
encodedRecordFieldList fs e =
case foldMap (recordField e) fs of
(nonNullable, []) ->
Expression.List nonNullable
([], nullable) ->
Expression.App "List.concat" $ Expression.List nullable
(nonNullable, nullable) ->
Expression.apps "Basics.++"
[ Expression.List nonNullable
, Expression.App "List.concat" $ Expression.List nullable
]
recordField
:: Expression v
-> (String, (Type Void, Expression v))
-> ([Expression v], [Expression v])
recordField e (fname, (type_, encoder))
| Aeson.omitNothingFields aesonOptions
, (Type.Global "Maybe.Maybe", _) <- Type.appsView type_ =
( []
, [ Expression.Case (Expression.App (Expression.Proj $ elmField fname) e)
[ ( Pattern.Con "Maybe.Nothing" []
, Bound.toScope $ Expression.List []
)
, ( Pattern.Con "Maybe.Just" [Pattern.Var 0]
, Bound.toScope $
Expression.List
[ Bound.F <$>
Expression.tuple
(jsonFieldName fname)
(Expression.App encoder (Expression.App (Expression.Proj $ elmField fname) e))
]
)
]
]
)
| otherwise =
( [ Expression.tuple
(jsonFieldName fname)
(Expression.App encoder (Expression.App (Expression.Proj $ elmField fname) e))
]
, []
)
constructorJSONName :: String -> Text
constructorJSONName = fromString . Aeson.constructorTagModifier aesonOptions
jsonFieldName :: String -> Expression v
jsonFieldName = Expression.String . fromString . Aeson.fieldLabelModifier aesonOptions
elmField :: String -> Name.Field
elmField = fromString . fieldLabelModifier options
elmConstr :: String -> Name.Qualified
elmConstr = Name.Qualified moduleName_ . fromString
encodeConstructorFields :: [(Type Void, Expression v)] -> Expression (Bound.Var Int v)
encodeConstructorFields [(_, encoder)] =
Expression.App (Bound.F <$> encoder) (pure $ Bound.B 0)
encodeConstructorFields constrFields =
Expression.apps
"Json.Encode.list"
[ "Basics.identity"
, Expression.List
[ Expression.App (Bound.F <$> encoder) (pure $ Bound.B index)
| (index, (_, encoder)) <- zip [0..] constrFields
]
]
encodeConstructors :: [(String, ConstructorShape (Type Void, Expression v))] -> Expression v -> Expression v
encodeConstructors [(constr, constrShape)] expr
| not $ Aeson.tagSingleConstructors aesonOptions =
Expression.Case expr
[ case constrShape of
ConstructorShape constrFields ->
( Pattern.Con (elmConstr constr) (Pattern.Var . fst <$> zip [0..] constrFields)
, Bound.toScope $ encodeConstructorFields constrFields
)
RecordConstructorShape recordFields ->
( Pattern.Con (elmConstr constr) [Pattern.Var 0]
, Bound.toScope $
Expression.App "Json.Encode.object" $
encodedRecordFieldList (second (second $ fmap Bound.F) <$> recordFields) $ pure $ Bound.B 0
)
]
encodeConstructors constrs expr
| Aeson.allNullaryToStringTag aesonOptions && all (nullary . snd) constrs =
Expression.Case expr
[ ( Pattern.Con (elmConstr constr) []
, Bound.toScope $
Expression.App "Json.Encode.string" $ Expression.String $ constructorJSONName constr
)
| (constr, _) <- constrs
]
encodeConstructors constrs expr =
case Aeson.sumEncoding aesonOptions of
Aeson.TaggedObject tagName contentsName ->
Expression.Case expr
[ case constrShape of
ConstructorShape constrFields ->
( Pattern.Con (elmConstr constr) (Pattern.Var . fst <$> zip [0..] constrFields)
, Bound.toScope $
Expression.App "Json.Encode.object" $
Expression.List $
tagTuple :
[ Expression.tuple
(Expression.String (fromString contentsName))
(encodeConstructorFields constrFields)
| not $ null constrFields
]
)
RecordConstructorShape recordFields ->
( Pattern.Con (elmConstr constr) [Pattern.Var 0]
, Bound.toScope $
Expression.App "Json.Encode.object" $
Expression.List [tagTuple] Expression.++
encodedRecordFieldList (second (second $ fmap Bound.F) <$> recordFields) (pure $ Bound.B 0)
)
| (constr, constrShape) <- constrs
, let
tagTuple =
Expression.tuple
(Expression.String (fromString tagName))
(Expression.App "Json.Encode.string" $ Expression.String $ constructorJSONName constr)
]
_ -> error "Only the DataAeson.TaggedObject sumEncoding is currently supported"
-------------
-- Int
instance HasElmType Int where
elmType =
"Basics.Int"
instance HasElmEncoder Aeson.Value Int where
elmEncoder =
"Json.Encode.int"
instance HasElmDecoder Aeson.Value Int where
elmDecoder =
"Json.Decode.int"
-- Int8
instance HasElmType Int.Int8 where
elmType =
"Basics.Int"
instance HasElmEncoder Aeson.Value Int.Int8 where
elmEncoder =
"Json.Encode.int"
instance HasElmDecoder Aeson.Value Int.Int8 where
elmDecoder =
"Json.Decode.int"
-- Int16
instance HasElmType Int.Int16 where
elmType =
"Basics.Int"
instance HasElmEncoder Aeson.Value Int.Int16 where
elmEncoder =
"Json.Encode.int"
instance HasElmDecoder Aeson.Value Int.Int16 where
elmDecoder =
"Json.Decode.int"
-- Int32
instance HasElmType Int.Int32 where
elmType =
"Basics.Int"
instance HasElmEncoder Aeson.Value Int.Int32 where
elmEncoder =
"Json.Encode.int"
instance HasElmDecoder Aeson.Value Int.Int32 where
elmDecoder =
"Json.Decode.int"
-- Word8
instance HasElmType Word.Word8 where
elmType =
"Basics.Int"
instance HasElmEncoder Aeson.Value Word.Word8 where
elmEncoder =
"Json.Encode.int"
instance HasElmDecoder Aeson.Value Word.Word8 where
elmDecoder =
"Json.Decode.int"
-- Word16
instance HasElmType Word.Word16 where
elmType =
"Basics.Int"
instance HasElmEncoder Aeson.Value Word.Word16 where
elmEncoder =
"Json.Encode.int"
instance HasElmDecoder Aeson.Value Word.Word16 where
elmDecoder =
"Json.Decode.int"
-- Word32
instance HasElmType Word.Word32 where
elmType =
"Basics.Int"
instance HasElmEncoder Aeson.Value Word.Word32 where
elmEncoder =
"Json.Encode.int"
instance HasElmDecoder Aeson.Value Word.Word32 where
elmDecoder =
"Json.Decode.int"
-- Double
instance HasElmType Double where
elmType =
"Basics.Float"
instance HasElmEncoder Aeson.Value Double where
elmEncoder =
"Json.Encode.float"
instance HasElmDecoder Aeson.Value Double where
elmDecoder =
"Json.Decode.float"
-- Float
instance HasElmType Float where
elmType =
"Basics.Float"
instance HasElmEncoder Aeson.Value Float where
elmEncoder =
"Json.Encode.float"
instance HasElmDecoder Aeson.Value Float where
elmDecoder =
"Json.Decode.float"
-- Bool
instance HasElmType Bool where
elmType =
"Basics.Bool"
instance HasElmEncoder Aeson.Value Bool where
elmEncoder =
"Json.Encode.bool"
instance HasElmDecoder Aeson.Value Bool where
elmDecoder =
"Json.Decode.bool"
-- Text
instance HasElmType Text where
elmType =
"String.String"
instance HasElmEncoder Text Text where
elmEncoder =
"Basics.identity"
instance HasElmDecoder Text Text where
elmDecoder =
"Basics.identity"
instance HasElmEncoder Text Char where
elmEncoder =
"String.fromChar"
instance HasElmEncoder Text Int where
elmEncoder =
"String.fromInt"
instance HasElmEncoder Text Int.Int8 where
elmEncoder =
"String.fromInt"
instance HasElmEncoder Text Int.Int16 where
elmEncoder =
"String.fromInt"
instance HasElmEncoder Text Int.Int32 where
elmEncoder =
"String.fromInt"
instance HasElmEncoder Text Word.Word8 where
elmEncoder =
"String.fromInt"
instance HasElmEncoder Text Word.Word16 where
elmEncoder =
"String.fromInt"
instance HasElmEncoder Text Word.Word32 where
elmEncoder =
"String.fromInt"
instance HasElmEncoder Text Double where
elmEncoder =
"String.fromFloat"
instance HasElmEncoder Text Float where
elmEncoder =
"String.fromFloat"
instance HasElmEncoder Aeson.Value Text where
elmEncoder =
"Json.Encode.string"
instance HasElmDecoder Aeson.Value Text where
elmDecoder =
"Json.Decode.string"
-- Char
instance HasElmType Char where
elmType =
"Char.Char"
instance HasElmEncoder Aeson.Value Char where
elmEncoder =
"Json.Encode.string" Expression.<< "String.fromChar"
instance HasElmDecoder Aeson.Value Char where
elmDecoder =
"Json.Decode.string" Expression.|>
Expression.App "Json.Decode.andThen"
(Expression.Lam $ Bound.toScope $
Expression.Case
(Expression.App "String.uncons" $ Expression.Var $ Bound.B ())
[ ( Pattern.Con "Maybe.Just" [Pattern.tuple (Pattern.Var 0) (Pattern.String "")]
, Bound.toScope $ Expression.App "Json.Decode.succeed" $ Expression.Var $ Bound.B 0
)
, ( Pattern.Wildcard
, Bound.toScope $ Expression.App "Json.Decode.fail" $ Expression.String "Not a char"
)
]
)
-- UTCTime
instance HasElmType UTCTime where
elmType =
"Time.Posix"
instance HasElmEncoder Aeson.Value UTCTime where
elmEncoder =
"Iso8601.encode"
instance HasElmDecoder Aeson.Value UTCTime where
elmDecoder =
"Iso8601.decoder"
-- Maybe
instance HasElmEncoder a b => HasElmEncoder (Maybe a) (Maybe b) where
elmEncoder = Expression.App "Maybe.map" (elmEncoder @a @b)
instance HasElmType a => HasElmType (Maybe a) where
elmType =
Type.App "Maybe.Maybe" (elmType @a)
instance HasElmEncoder Aeson.Value a => HasElmEncoder Aeson.Value (Maybe a) where
elmEncoder =
Expression.apps "Maybe.Extra.unwrap" ["Json.Encode.null", elmEncoder @Aeson.Value @a]
instance HasElmDecoder Aeson.Value a => HasElmDecoder Aeson.Value (Maybe a) where
elmDecoder =
Expression.App "Json.Decode.nullable" (elmDecoder @Aeson.Value @a)
-- Vector
instance HasElmType a => HasElmType (Vector a) where
elmType =
Type.App "Array.Array" (elmType @a)
instance HasElmEncoder Aeson.Value a => HasElmEncoder Aeson.Value (Vector a) where
elmEncoder =
Expression.App "Json.Encode.array" (elmEncoder @Aeson.Value @a)
instance HasElmDecoder Aeson.Value a => HasElmDecoder Aeson.Value (Vector a) where
elmDecoder =
Expression.App "Json.Decode.array" (elmDecoder @Aeson.Value @a)
-- List
instance HasElmType a => HasElmType [a] where
elmType =
Type.App "List.List" (elmType @a)
instance HasElmEncoder Aeson.Value a => HasElmEncoder Aeson.Value [a] where
elmEncoder =
Expression.App "Json.Encode.list" (elmEncoder @Aeson.Value @a)
instance HasElmDecoder Aeson.Value a => HasElmDecoder Aeson.Value [a] where
elmDecoder =
Expression.App "Json.Decode.list" (elmDecoder @Aeson.Value @a)
-- Tuple
instance (HasElmType a, HasElmType b) => HasElmType (a, b) where
elmType =
Type.apps "Basics.," [elmType @a, elmType @b]
instance (HasElmEncoder Aeson.Value a, HasElmEncoder Aeson.Value b) => HasElmEncoder Aeson.Value (a, b) where
elmEncoder =
Expression.Lam $ Bound.toScope $
Expression.Case (pure $ Bound.B ())
[ ( Pattern.tuple (Pattern.Var 0) (Pattern.Var 1)
, Bound.toScope $
Expression.apps
"Json.Encode.list"
[ "Basics.identity"
, Expression.List
[ Expression.App (elmEncoder @Aeson.Value @a) $ pure $ Bound.B 0
, Expression.App (elmEncoder @Aeson.Value @b) $ pure $ Bound.B 1
]
]
)
]
instance (HasElmDecoder Aeson.Value a, HasElmDecoder Aeson.Value b) => HasElmDecoder Aeson.Value (a, b) where
elmDecoder =
Expression.apps
"Json.Decode.map2"
[ "Tuple.pair"
, Expression.apps "Json.Decode.index" [Expression.Int 0, elmDecoder @Aeson.Value @a]
, Expression.apps "Json.Decode.index" [Expression.Int 1, elmDecoder @Aeson.Value @b]
]
-- | A shorthand for a list of the type definitions for
-- @'jsonDefinitions' \@MyType@ is a shorthand for creating a list of its
-- 'elmDefinition', @'elmEncoderDefinition' \@'Aeson.Value'@, and
-- @'elmDecoderDefinition' \@'Aeson.Value'@.
jsonDefinitions :: forall t. (HasElmEncoder Aeson.Value t, HasElmDecoder Aeson.Value t) => [Definition]
jsonDefinitions =
catMaybes
[ elmDefinition @t
, elmEncoderDefinition @Aeson.Value @t
, elmDecoderDefinition @Aeson.Value @t
]