Elminator

Generate Elm type definitions, encoders and decoders from Haskell data types.

  {-#Language ScopedTypeVariables#-}
  {-#Language FlexibleInstances#-}
  {-#Language DeriveAnyClass#-}
  {-#Language OverloadedStrings#-}

  module Lib  where

  import Elminator
  import GHC.Generics

  data SingleCon = SingleCon (Maybe Int) String deriving (Generic, ToHType)
  data WithMaybesPoly a b =
    WithMaybesPoly
      { mbpF1 :: Maybe a
      , mbpF2 :: Maybe b
      }
    deriving (Generic, ToHType)

Here is how we generate Elm source for the above defined types.

{-#Language OverloadedStrings#-}
{-#Language TemplateHaskell#-}

module CodeGen where

import Data.Proxy
import Elminator
import Data.Text

import Lib

elmSource :: Text
elmSource = $(generateFor Elm19 myDefaultOptions (Just "./elm-app/src/Autogen.elm") $ do
  include (Proxy :: Proxy SingleCon) $ Everything Mono
  include (Proxy :: Proxy (WithMaybesPoly (Maybe String) Float)) $ Definiton Poly

Documentation

include :: ToHType a => Proxy a -> GenOption -> Builder

Include the elm source for the Haskell type specified by the proxy argument. The second argument decides which components will be included and if the generated type will be polymorphic.

generateFor :: ElmVersion -> Options -> Maybe FilePath -> Builder -> Q Exp

Return the generated Elm code in a template haskell splice and optionally write to a Elm source file at the same time. The second argument is the Options type from Aeson library. Use include calls to build the Builder value.

data ElmVersion

Specify Elm version to generate code for

Constructors

Elm19

data HType

This type holds the type information we get from generics. Only the HExternal constructor is supposed to be used by the programmer to implement ToHType instances for entites that are predefined in Elm. A sample can be seen below.

Here, let `MyExtType a b` be a type which has the corresponding type, encoders and decoders predefined in Elm in a module named Lib. Here is how you can implement a ToHType instance for this type so that your autogenerated types can have fields of type `MyExtType a b`.

  instance (ToHType a, ToHType b) => ToHType (MyExtType a b) where
    toHType _ = do
      ha <- toHType (Proxy :: Proxy a)
      hb <- toHType (Proxy :: Proxy b)
      pure $
        HExternal
          (ExInfo
            (ExItem "Lib" "MyExtType") 
            (Just $ ExItem "Lib" "encodeMyExtType")
            (Just $ ExItem "Lib" "decodeMyExtType"))
          [ha, hb]

Constructors

HUDef UDefData

HMaybe HType

HList HType

HPrimitive MData

HRecursive MData

HExternal ExInfo [HType]

Instances

Show HType

Defined in Elminator.Generics.Simple

Methods

showsPrec :: Int -> HType -> ShowS

show :: HType -> String

showList :: [HType] -> ShowS

class ToHType f where

Minimal complete definition

Nothing

Methods

toHType :: Proxy f -> HState HType

toHType :: (ToHTArgs (ExtractTArgs f), Generic f, ToHType_ (Rep f)) => Proxy f -> HState HType

Instances

ToHType Bool

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy Bool -> HState HType

ToHType Char

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy Char -> HState HType

ToHType Float

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy Float -> HState HType

ToHType Int

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy Int -> HState HType

ToHType ()

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy () -> HState HType

ToHType a => ToHType [a]

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy [a] -> HState HType

ToHType a => ToHType (Maybe a)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (Maybe a) -> HState HType

(ToHType a, ToHType b) => ToHType (Either a b)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (Either a b) -> HState HType

(ToHType a1, ToHType a2) => ToHType (a1, a2)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (a1, a2) -> HState HType

(ToHType a1, ToHType a2, ToHType a3) => ToHType (a1, a2, a3)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (a1, a2, a3) -> HState HType

(ToHType a1, ToHType a2, ToHType a3, ToHType a4) => ToHType (a1, a2, a3, a4)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (a1, a2, a3, a4) -> HState HType

(ToHType a1, ToHType a2, ToHType a3, ToHType a4, ToHType a5) => ToHType (a1, a2, a3, a4, a5)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (a1, a2, a3, a4, a5) -> HState HType

(ToHType a1, ToHType a2, ToHType a3, ToHType a4, ToHType a5, ToHType a6) => ToHType (a1, a2, a3, a4, a5, a6)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (a1, a2, a3, a4, a5, a6) -> HState HType

(ToHType a1, ToHType a2, ToHType a3, ToHType a4, ToHType a5, ToHType a6, ToHType a7) => ToHType (a1, a2, a3, a4, a5, a6, a7)

Defined in Elminator.Generics.Simple

Methods

toHType :: Proxy (a1, a2, a3, a4, a5, a6, a7) -> HState HType

data ExItem

Constructors

ExItem

Fields

• extModuleName :: Text
• extSymbol :: Text

Instances

Eq ExItem

Defined in Elminator.Generics.Simple

Methods

(==) :: ExItem -> ExItem -> Bool

(/=) :: ExItem -> ExItem -> Bool

Show ExItem

Defined in Elminator.Generics.Simple

Methods

showsPrec :: Int -> ExItem -> ShowS

show :: ExItem -> String

showList :: [ExItem] -> ShowS

data ExInfo

Constructors

ExInfo

Fields

• exType :: ExItem
• exEncoder :: Maybe ExItem
• exDecoder :: Maybe ExItem

Instances

Eq ExInfo

Defined in Elminator.Generics.Simple

Methods

(==) :: ExInfo -> ExInfo -> Bool

(/=) :: ExInfo -> ExInfo -> Bool

Show ExInfo

Defined in Elminator.Generics.Simple

Methods

showsPrec :: Int -> ExInfo -> ShowS

show :: ExInfo -> String

showList :: [ExInfo] -> ShowS

type Builder = State GenConfig ()

data GenOption

Decides which among type definiton, encoder and decoder will be included for a type. The poly config value decides wether the included type definition will be polymorphic.

Constructors

Definiton PolyConfig

EncoderDecoder

Everything PolyConfig

Instances

Show GenOption

Defined in Elminator.Lib

Methods

showsPrec :: Int -> GenOption -> ShowS

show :: GenOption -> String

showList :: [GenOption] -> ShowS

data PolyConfig

Decides wether the type definition will be polymorphic.

Constructors

Mono

Poly

Instances

Show PolyConfig

Defined in Elminator.Lib

Methods

showsPrec :: Int -> PolyConfig -> ShowS

show :: PolyConfig -> String

showList :: [PolyConfig] -> ShowS