Servant.Elm

Basic usage:

import MyLib (MyServantApiType)
import Servant.Elm

spec :: Spec
spec = Spec ["Generated", "MyApi"]
            (defElmImports : generateElmForAPI (Proxy :: Proxy MyServantApiType))

main :: IO ()
main = specsToDir [spec] "my-elm-dir"

Documentation

generateElmForAPI :: (HasForeign LangElm EType api, GenerateList EType (Foreign EType api)) => Proxy api -> [Text]

Generate Elm code for the API with default options.

Returns a list of Elm functions to query your Servant API from Elm.

You could spit these out to a file and call them from your Elm code, but you would be better off creating a Spec with the result and using specsToDir, which handles the module name for you.

generateElmForAPIWith :: (HasForeign LangElm EType api, GenerateList EType (Foreign EType api)) => ElmOptions -> Proxy api -> [Text]

Generate Elm code for the API with custom options.

generateElmModule :: (HasForeign LangElm EType api, GenerateList EType (Foreign EType api)) => Namespace -> Text -> FilePath -> [DefineElm] -> Proxy api -> IO ()

Calls generateElmModuleWith with defElmOptions.

generateElmModuleWith :: (HasForeign LangElm EType api, GenerateList EType (Foreign EType api)) => ElmOptions -> Namespace -> Text -> FilePath -> [DefineElm] -> Proxy api -> IO ()

Helper to generate a complete Elm module given a list of Elm type definitions and an API.

data ElmOptions

Options to configure how code is generated.

Constructors

ElmOptions

Fields

• urlPrefix :: UrlPrefix

  The protocol, host and any path prefix to be used as the base for all requests.

  Example: Static "https://mydomain.com/api/v1"

  When Dynamic, the generated Elm functions take the base URL as the first argument.

• elmTypeAlterations :: EType -> EType

  Alterations to perform on ETypes before code generation.

• elmAlterations :: ETypeDef -> ETypeDef

  Alterations to perform on ETypeDefs before code generation.

• emptyResponseElmTypes :: [EType]

  Types that represent an empty Http response.

• stringElmTypes :: [EType]

  Types that represent a String.

data UrlPrefix

Constructors

Static Text

Dynamic

defElmOptions :: ElmOptions

Default options for generating Elm code.

The default options are:

{ urlPrefix =
    Static ""
, elmAlterations =
    Elm.defaultTypeAlterations
, emptyResponseElmTypes =
    [ getType (Proxy :: Proxy ()) ]
, stringElmTypes =
    [ getType (Proxy :: Proxy String)
    , getType (Proxy :: Proxy T.Text) ]
}

defElmImports :: Text

Default imports required by generated Elm code.

You probably want to include this at the top of your generated Elm module.

The default required imports are:

import Json.Decode
import Json.Encode exposing (Value)
-- The following module comes from bartavelle/json-helpers
import Json.Helpers exposing (..)
import Dict exposing (Dict)
import Set
import Http
import String
import Url.Builder

defaultOptions :: Options

Convenience re-exports from the Elm module

data DefineElm where

Existential quantification wrapper for lists of type definitions

Constructors

DefineElm :: forall a. IsElmDefinition a => Proxy a -> DefineElm

data EType

Type construction : type variables, type constructors, tuples and type application.

Constructors

ETyVar ETVar

ETyCon ETCon

ETyApp EType EType

ETyTuple Int

Instances

Eq EType

Defined in Elm.TyRep

Methods

(==) :: EType -> EType -> Bool

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

Ord EType

Defined in Elm.TyRep

Methods

compare :: EType -> EType -> Ordering

(<) :: EType -> EType -> Bool

(<=) :: EType -> EType -> Bool

(>) :: EType -> EType -> Bool

(>=) :: EType -> EType -> Bool

max :: EType -> EType -> EType

min :: EType -> EType -> EType

Show EType

Defined in Elm.TyRep

Methods

showsPrec :: Int -> EType -> ShowS

show :: EType -> String

showList :: [EType] -> ShowS

ElmRenderable EType

Defined in Elm.TyRender

Methods

renderElm :: EType -> String

Typeable a => HasForeignType LangElm EType (a :: Type)

Defined in Servant.Elm.Internal.Foreign

Methods

typeFor :: Proxy LangElm -> Proxy EType -> Proxy a -> EType

Typeable a => HasForeignType LangElm EType (Headers b a :: Type)

Defined in Servant.Elm.Internal.Foreign

Methods

typeFor :: Proxy LangElm -> Proxy EType -> Proxy (Headers b a) -> EType

defaultTypeAlterations :: EType -> EType

toElmType :: Typeable a => Proxy a -> EType

Get an elm-bridge type representation for a Haskell type. This can be used to render the type declaration via ElmRenderable or the the JSON serializer/parser names via jsonSerForType and jsonParserForType.

deriveBoth :: Options -> Name -> Q [Dec]

Equivalent to running both deriveJSON and deriveElmDef with the same options, so as to ensure the code on the Haskell and Elm size is synchronized.

deriveElmDef :: Options -> Name -> Q [Dec]

Just derive the elm-bridge definitions for generating the serialization/deserialization code. It must be kept synchronized with the Haskell code manually.

Convenience re-exports from Data.Proxy

data Proxy (t :: k) :: forall k. k -> Type

Proxy is a type that holds no data, but has a phantom parameter of arbitrary type (or even kind). Its use is to provide type information, even though there is no value available of that type (or it may be too costly to create one).

Historically, Proxy :: Proxy a is a safer alternative to the 'undefined :: a' idiom.

>>> Proxy :: Proxy (Void, Int -> Int)
Proxy

Proxy can even hold types of higher kinds,

>>> Proxy :: Proxy Either
Proxy

>>> Proxy :: Proxy Functor
Proxy

>>> Proxy :: Proxy complicatedStructure
Proxy

Constructors

Proxy

Instances

Generic1 (Proxy :: k -> Type)

Defined in GHC.Generics

Associated Types

type Rep1 Proxy :: k -> Type

Methods

from1 :: Proxy a -> Rep1 Proxy a

to1 :: Rep1 Proxy a -> Proxy a

Monad (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

(>>=) :: Proxy a -> (a -> Proxy b) -> Proxy b

(>>) :: Proxy a -> Proxy b -> Proxy b

return :: a -> Proxy a

fail :: String -> Proxy a

Functor (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

fmap :: (a -> b) -> Proxy a -> Proxy b

(<$) :: a -> Proxy b -> Proxy a

Applicative (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

pure :: a -> Proxy a

(<*>) :: Proxy (a -> b) -> Proxy a -> Proxy b

liftA2 :: (a -> b -> c) -> Proxy a -> Proxy b -> Proxy c

(*>) :: Proxy a -> Proxy b -> Proxy b

(<*) :: Proxy a -> Proxy b -> Proxy a

Foldable (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in Data.Foldable

Methods

fold :: Monoid m => Proxy m -> m

foldMap :: Monoid m => (a -> m) -> Proxy a -> m

foldr :: (a -> b -> b) -> b -> Proxy a -> b

foldr' :: (a -> b -> b) -> b -> Proxy a -> b

foldl :: (b -> a -> b) -> b -> Proxy a -> b

foldl' :: (b -> a -> b) -> b -> Proxy a -> b

foldr1 :: (a -> a -> a) -> Proxy a -> a

foldl1 :: (a -> a -> a) -> Proxy a -> a

toList :: Proxy a -> [a]

null :: Proxy a -> Bool

length :: Proxy a -> Int

elem :: Eq a => a -> Proxy a -> Bool

maximum :: Ord a => Proxy a -> a

minimum :: Ord a => Proxy a -> a

sum :: Num a => Proxy a -> a

product :: Num a => Proxy a -> a

Traversable (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Proxy a -> f (Proxy b)

sequenceA :: Applicative f => Proxy (f a) -> f (Proxy a)

mapM :: Monad m => (a -> m b) -> Proxy a -> m (Proxy b)

sequence :: Monad m => Proxy (m a) -> m (Proxy a)

Contravariant (Proxy :: Type -> Type)

Defined in Data.Functor.Contravariant

Methods

contramap :: (a -> b) -> Proxy b -> Proxy a

(>$) :: b -> Proxy b -> Proxy a

Representable (Proxy :: Type -> Type)

Defined in Data.Functor.Rep

Associated Types

type Rep Proxy :: Type

Methods

tabulate :: (Rep Proxy -> a) -> Proxy a

index :: Proxy a -> Rep Proxy -> a

Alternative (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in Data.Proxy

Methods

empty :: Proxy a

(<|>) :: Proxy a -> Proxy a -> Proxy a

some :: Proxy a -> Proxy [a]

many :: Proxy a -> Proxy [a]

MonadPlus (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in Data.Proxy

Methods

mzero :: Proxy a

mplus :: Proxy a -> Proxy a -> Proxy a

Bounded (Proxy t)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

minBound :: Proxy t

maxBound :: Proxy t

Enum (Proxy s)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

succ :: Proxy s -> Proxy s

pred :: Proxy s -> Proxy s

toEnum :: Int -> Proxy s

fromEnum :: Proxy s -> Int

enumFrom :: Proxy s -> [Proxy s]

enumFromThen :: Proxy s -> Proxy s -> [Proxy s]

enumFromTo :: Proxy s -> Proxy s -> [Proxy s]

enumFromThenTo :: Proxy s -> Proxy s -> Proxy s -> [Proxy s]

Eq (Proxy s)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

(==) :: Proxy s -> Proxy s -> Bool

(/=) :: Proxy s -> Proxy s -> Bool

Ord (Proxy s)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

compare :: Proxy s -> Proxy s -> Ordering

(<) :: Proxy s -> Proxy s -> Bool

(<=) :: Proxy s -> Proxy s -> Bool

(>) :: Proxy s -> Proxy s -> Bool

(>=) :: Proxy s -> Proxy s -> Bool

max :: Proxy s -> Proxy s -> Proxy s

min :: Proxy s -> Proxy s -> Proxy s

Read (Proxy t)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

readsPrec :: Int -> ReadS (Proxy t)

readList :: ReadS [Proxy t]

readPrec :: ReadPrec (Proxy t)

readListPrec :: ReadPrec [Proxy t]

Show (Proxy s)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

showsPrec :: Int -> Proxy s -> ShowS

show :: Proxy s -> String

showList :: [Proxy s] -> ShowS

Ix (Proxy s)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

range :: (Proxy s, Proxy s) -> [Proxy s]

index :: (Proxy s, Proxy s) -> Proxy s -> Int

unsafeIndex :: (Proxy s, Proxy s) -> Proxy s -> Int

inRange :: (Proxy s, Proxy s) -> Proxy s -> Bool

rangeSize :: (Proxy s, Proxy s) -> Int

unsafeRangeSize :: (Proxy s, Proxy s) -> Int

Generic (Proxy t)

Defined in GHC.Generics

Associated Types

type Rep (Proxy t) :: Type -> Type

Methods

from :: Proxy t -> Rep (Proxy t) x

to :: Rep (Proxy t) x -> Proxy t

Semigroup (Proxy s)

Since: base-4.9.0.0

Defined in Data.Proxy

Methods

(<>) :: Proxy s -> Proxy s -> Proxy s

sconcat :: NonEmpty (Proxy s) -> Proxy s

stimes :: Integral b => b -> Proxy s -> Proxy s

Monoid (Proxy s)

Since: base-4.7.0.0

Defined in Data.Proxy

Methods

mempty :: Proxy s

mappend :: Proxy s -> Proxy s -> Proxy s

mconcat :: [Proxy s] -> Proxy s

type Rep1 (Proxy :: k -> Type)

Since: base-4.6.0.0

Defined in GHC.Generics

type Rep1 (Proxy :: k -> Type) = D1 (MetaData "Proxy" "Data.Proxy" "base" False) (C1 (MetaCons "Proxy" PrefixI False) (U1 :: k -> Type))

type Rep (Proxy :: Type -> Type)

Defined in Data.Functor.Rep

type Rep (Proxy :: Type -> Type) = Void

type Rep (Proxy t)

Since: base-4.6.0.0

Defined in GHC.Generics

type Rep (Proxy t) = D1 (MetaData "Proxy" "Data.Proxy" "base" False) (C1 (MetaCons "Proxy" PrefixI False) (U1 :: Type -> Type))