543 lines
19 KiB
Haskell
543 lines
19 KiB
Haskell
{-# LANGUAGE CPP #-}
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{-# LANGUAGE ConstraintKinds #-}
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{-# LANGUAGE DeriveDataTypeable #-}
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{-# LANGUAGE FlexibleContexts #-}
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{-# LANGUAGE FlexibleInstances #-}
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{-# LANGUAGE GeneralizedNewtypeDeriving #-}
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{-# LANGUAGE MultiParamTypeClasses #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE PolyKinds #-}
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{-# LANGUAGE ScopedTypeVariables #-}
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{-# LANGUAGE TemplateHaskell #-}
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{-# LANGUAGE TypeFamilies #-}
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{-# LANGUAGE TypeOperators #-}
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{-# LANGUAGE UndecidableInstances #-}
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module Servant.Foreign.Internal where
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import Prelude ()
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import Prelude.Compat
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import Control.Lens
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(Getter, makeLenses, makePrisms, (%~), (&), (.~), (<>~))
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import Data.Data
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(Data)
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import Data.Proxy
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import Data.String
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import Data.Text
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import Data.Text.Encoding
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(decodeUtf8)
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import Data.Typeable
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(Typeable)
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import GHC.TypeLits
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import qualified Network.HTTP.Types as HTTP
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import Servant.API
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import Servant.API.Modifiers
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(RequiredArgument)
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import Servant.API.TypeLevel
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-- | Canonical name of the endpoint, can be used to generate a function name.
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--
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-- You can use the functions in "Servant.Foreign.Inflections", like 'Servant.Foreign.Inflections.camelCase' to transform to `Text`.
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newtype FunctionName = FunctionName { unFunctionName :: [Text] }
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deriving (Data, Show, Eq, Semigroup, Monoid, Typeable)
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makePrisms ''FunctionName
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-- | See documentation of 'Arg'
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newtype PathSegment = PathSegment { unPathSegment :: Text }
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deriving (Data, Show, Eq, IsString, Semigroup, Monoid, Typeable)
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makePrisms ''PathSegment
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-- | Maps a name to the foreign type that belongs to the annotated value.
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--
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-- Used for header args, query args, and capture args.
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data Arg ftype = Arg
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{ _argName :: PathSegment
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-- ^ The name to be captured.
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--
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-- Only for capture args it really denotes a path segment.
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, _argType :: ftype
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-- ^ Foreign type the associated value will have
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}
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deriving (Data, Eq, Show, Typeable)
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makeLenses ''Arg
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argPath :: Getter (Arg ftype) Text
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argPath = argName . _PathSegment
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data SegmentType ftype
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= Static PathSegment
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-- ^ Static path segment.
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--
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-- @"foo\/bar\/baz"@
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--
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-- contains the static segments @"foo"@, @"bar"@ and @"baz"@.
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| Cap (Arg ftype)
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-- ^ A capture.
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--
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-- @"user\/{userid}\/name"@
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--
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-- would capture the arg @userid@ with type @ftype@.
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deriving (Data, Eq, Show, Typeable)
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makePrisms ''SegmentType
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-- | A part of the Url’s path.
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newtype Segment ftype = Segment { unSegment :: SegmentType ftype }
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deriving (Data, Eq, Show, Typeable)
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makePrisms ''Segment
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-- | Whether a segment is a 'Cap'.
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isCapture :: Segment ftype -> Bool
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isCapture (Segment (Cap _)) = True
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isCapture _ = False
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-- | Crashing Arg extraction from segment, TODO: remove
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captureArg :: Segment ftype -> Arg ftype
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captureArg (Segment (Cap s)) = s
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captureArg _ = error "captureArg called on non capture"
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-- TODO: remove, unnecessary indirection
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type Path ftype = [Segment ftype]
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-- | Type of a 'QueryArg'.
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data ArgType
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= Normal
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| Flag
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| List
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deriving (Data, Eq, Show, Typeable)
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makePrisms ''ArgType
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-- | Url Query argument.
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--
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-- Urls can contain query arguments, which is a list of key-value pairs.
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-- In a typical url, query arguments look like this:
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--
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-- @?foo=bar&alist[]=el1&alist[]=el2&aflag@
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--
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-- Each pair can be
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--
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-- * @?foo=bar@: a plain key-val pair, either optional or required ('QueryParam')
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-- * @?aflag@: a flag (no value, implicitly Bool with default `false` if it’s missing) ('QueryFlag')
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-- * @?alist[]=el1&alist[]=el2@: list of values ('QueryParams')
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--
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-- @_queryArgType@ will be set accordingly.
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--
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-- For the plain key-val pairs ('QueryParam'), @_queryArgName@’s @ftype@ will be wrapped in a @Maybe@ if the argument is optional.
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data QueryArg ftype = QueryArg
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{ _queryArgName :: Arg ftype
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-- ^ Name and foreign type of the argument. Will be wrapped in `Maybe` if the query is optional and in a `[]` if the query is a list
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, _queryArgType :: ArgType
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-- ^ one of normal/plain, list or flag
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}
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deriving (Data, Eq, Show, Typeable)
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makeLenses ''QueryArg
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data HeaderArg ftype =
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-- | The name of the header and the foreign type of its value.
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HeaderArg
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{ _headerArg :: Arg ftype }
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-- | Unused, will never be set.
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--
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-- TODO: remove
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| ReplaceHeaderArg
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{ _headerArg :: Arg ftype
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, _headerPattern :: Text
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}
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deriving (Data, Eq, Show, Typeable)
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makeLenses ''HeaderArg
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makePrisms ''HeaderArg
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-- | Full endpoint url, with all captures and parameters
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data Url ftype = Url
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{ _path :: Path ftype
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-- ^ Url path, list of either static segments or captures
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--
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-- @"foo\/{id}\/bar"@
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, _queryStr :: [QueryArg ftype]
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-- ^ List of query args
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--
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-- @"?foo=bar&a=b"@
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, _frag :: Maybe ftype
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-- ^ Url fragment.
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--
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-- Not sent to the HTTP server, so only useful for frontend matters (e.g. inter-page linking).
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--
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-- @#fragmentText@
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}
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deriving (Data, Eq, Show, Typeable)
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defUrl :: Url ftype
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defUrl = Url [] [] Nothing
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makeLenses ''Url
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-- | See documentation of '_reqBodyContentType'
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data ReqBodyContentType = ReqBodyJSON | ReqBodyMultipart
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deriving (Data, Eq, Show, Read)
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-- | Full description of an endpoint in your API, generated by 'listFromAPI'. It should give you all the information needed to generate foreign language bindings.
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--
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-- Every field containing @ftype@ will use the foreign type mapping specified via 'HasForeignType' (see its docstring on how to set that up).
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--
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-- See https://docs.servant.dev/en/stable/tutorial/ApiType.html for accessible documentation of the possible content of an endpoint.
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data Req ftype = Req
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{ _reqUrl :: Url ftype
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-- ^ Full list of URL segments, including captures
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, _reqMethod :: HTTP.Method
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-- ^ @\"GET\"@\/@\"POST\"@\/@\"PUT\"@\/…
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, _reqHeaders :: [HeaderArg ftype]
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-- ^ Headers required by this endpoint, with their type
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, _reqBody :: Maybe ftype
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-- ^ Foreign type of the expected request body ('ReqBody'), if any
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, _reqReturnType :: Maybe ftype
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-- ^ The foreign type of the response, if any
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, _reqFuncName :: FunctionName
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-- ^ The URL segments rendered in a way that they can be easily concatenated into a canonical function name
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, _reqBodyContentType :: ReqBodyContentType
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-- ^ The content type the request body is transferred as.
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--
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-- This is a severe limitation of @servant-foreign@ currently,
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-- as we only allow the content type to be `JSON`
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-- no user-defined content types. ('ReqBodyMultipart' is not
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-- actually implemented.)
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--
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-- Thus, any routes looking like this will work:
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--
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-- @"foo" :> Get '[JSON] Foo@
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--
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-- while routes like
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--
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-- @"foo" :> Get '[MyFancyContentType] Foo@
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--
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-- will fail with an error like
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--
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-- @• JSON expected in list '[MyFancyContentType]@
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}
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deriving (Data, Eq, Show, Typeable)
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makeLenses ''Req
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defReq :: Req ftype
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defReq = Req defUrl "GET" [] Nothing Nothing (FunctionName []) ReqBodyJSON
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-- | 'HasForeignType' maps Haskell types with types in the target
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-- language of your backend. For example, let's say you're
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-- implementing a backend to some language __X__, and you want
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-- a Text representation of each input/output type mentioned in the API:
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--
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-- > -- First you need to create a dummy type to parametrize your
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-- > -- instances.
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-- > data LangX
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-- >
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-- > -- Otherwise you define instances for the types you need
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-- > instance HasForeignType LangX Text Int where
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-- > typeFor _ _ _ = "intX"
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-- >
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-- > -- Or for example in case of lists
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-- > instance HasForeignType LangX Text a => HasForeignType LangX Text [a] where
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-- > typeFor lang ftype _ = "listX of " <> typeFor lang ftype (Proxy :: Proxy a)
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--
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-- Finally to generate list of information about all the endpoints for
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-- an API you create a function of a form:
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--
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-- > getEndpoints :: (HasForeign LangX Text api, GenerateList Text (Foreign Text api))
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-- > => Proxy api -> [Req Text]
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-- > getEndpoints api = listFromAPI (Proxy :: Proxy LangX) (Proxy :: Proxy Text) api
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--
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-- > -- If language __X__ is dynamically typed then you can use
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-- > -- a predefined NoTypes parameter with the NoContent output type:
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--
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-- > getEndpoints :: (HasForeign NoTypes NoContent api, GenerateList Text (Foreign NoContent api))
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-- > => Proxy api -> [Req NoContent]
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-- > getEndpoints api = listFromAPI (Proxy :: Proxy NoTypes) (Proxy :: Proxy NoContent) api
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-- >
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--
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class HasForeignType lang ftype a where
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typeFor :: Proxy lang -> Proxy ftype -> Proxy a -> ftype
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-- | The language definition without any foreign types. It can be used for dynamic languages which do not /do/ type annotations.
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data NoTypes
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-- | Use if the foreign language does not have any types.
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instance HasForeignType NoTypes NoContent a where
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typeFor _ _ _ = NoContent
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-- | Implementation of the Servant framework types.
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--
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-- Relevant instances: Everything containing 'HasForeignType'.
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class HasForeign lang ftype (api :: *) where
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type Foreign ftype api :: *
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foreignFor :: Proxy lang -> Proxy ftype -> Proxy api -> Req ftype -> Foreign ftype api
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instance (HasForeign lang ftype a, HasForeign lang ftype b)
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=> HasForeign lang ftype (a :<|> b) where
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type Foreign ftype (a :<|> b) = Foreign ftype a :<|> Foreign ftype b
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foreignFor lang ftype Proxy req =
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foreignFor lang ftype (Proxy :: Proxy a) req
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:<|> foreignFor lang ftype (Proxy :: Proxy b) req
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data EmptyForeignAPI = EmptyForeignAPI
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instance HasForeign lang ftype EmptyAPI where
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type Foreign ftype EmptyAPI = EmptyForeignAPI
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foreignFor Proxy Proxy Proxy _ = EmptyForeignAPI
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instance (KnownSymbol sym, HasForeignType lang ftype t, HasForeign lang ftype api)
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=> HasForeign lang ftype (Capture' mods sym t :> api) where
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type Foreign ftype (Capture' mods sym t :> api) = Foreign ftype api
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foreignFor lang Proxy Proxy req =
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foreignFor lang Proxy (Proxy :: Proxy api) $
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req & reqUrl . path <>~ [Segment (Cap arg)]
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& reqFuncName . _FunctionName %~ (++ ["by", str])
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where
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str = pack . symbolVal $ (Proxy :: Proxy sym)
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ftype = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy t)
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arg = Arg
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{ _argName = PathSegment str
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, _argType = ftype }
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instance (KnownSymbol sym, HasForeignType lang ftype [t], HasForeign lang ftype sublayout)
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=> HasForeign lang ftype (CaptureAll sym t :> sublayout) where
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type Foreign ftype (CaptureAll sym t :> sublayout) = Foreign ftype sublayout
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foreignFor lang Proxy Proxy req =
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foreignFor lang Proxy (Proxy :: Proxy sublayout) $
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req & reqUrl . path <>~ [Segment (Cap arg)]
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& reqFuncName . _FunctionName %~ (++ ["by", str])
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where
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str = pack . symbolVal $ (Proxy :: Proxy sym)
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ftype = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy [t])
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arg = Arg
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{ _argName = PathSegment str
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, _argType = ftype }
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instance (Elem JSON list, HasForeignType lang ftype a, ReflectMethod method)
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=> HasForeign lang ftype (Verb method status list a) where
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type Foreign ftype (Verb method status list a) = Req ftype
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foreignFor lang Proxy Proxy req =
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req & reqFuncName . _FunctionName %~ (methodLC :)
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& reqMethod .~ method
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& reqReturnType .~ Just retType
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where
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retType = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy a)
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method = reflectMethod (Proxy :: Proxy method)
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methodLC = toLower $ decodeUtf8 method
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instance (HasForeignType lang ftype NoContent, ReflectMethod method)
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=> HasForeign lang ftype (NoContentVerb method) where
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type Foreign ftype (NoContentVerb method) = Req ftype
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foreignFor lang Proxy Proxy req =
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req & reqFuncName . _FunctionName %~ (methodLC :)
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& reqMethod .~ method
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& reqReturnType .~ Just retType
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where
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retType = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy NoContent)
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method = reflectMethod (Proxy :: Proxy method)
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methodLC = toLower $ decodeUtf8 method
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-- | TODO: doesn't taking framing into account.
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instance (ct ~ JSON, HasForeignType lang ftype a, ReflectMethod method)
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=> HasForeign lang ftype (Stream method status framing ct a) where
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type Foreign ftype (Stream method status framing ct a) = Req ftype
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foreignFor lang Proxy Proxy req =
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req & reqFuncName . _FunctionName %~ (methodLC :)
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& reqMethod .~ method
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& reqReturnType .~ Just retType
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where
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retType = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy a)
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method = reflectMethod (Proxy :: Proxy method)
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methodLC = toLower $ decodeUtf8 method
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instance (KnownSymbol sym, HasForeignType lang ftype (RequiredArgument mods a), HasForeign lang ftype api)
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=> HasForeign lang ftype (Header' mods sym a :> api) where
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type Foreign ftype (Header' mods sym a :> api) = Foreign ftype api
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foreignFor lang Proxy Proxy req =
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foreignFor lang Proxy subP $ req & reqHeaders <>~ [HeaderArg arg]
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where
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hname = pack . symbolVal $ (Proxy :: Proxy sym)
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arg = Arg
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{ _argName = PathSegment hname
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, _argType = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy (RequiredArgument mods a)) }
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subP = Proxy :: Proxy api
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instance (KnownSymbol sym, HasForeignType lang ftype (RequiredArgument mods a), HasForeign lang ftype api)
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=> HasForeign lang ftype (QueryParam' mods sym a :> api) where
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type Foreign ftype (QueryParam' mods sym a :> api) = Foreign ftype api
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foreignFor lang Proxy Proxy req =
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foreignFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy api) $
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req & reqUrl.queryStr <>~ [QueryArg arg Normal]
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where
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str = pack . symbolVal $ (Proxy :: Proxy sym)
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arg = Arg
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{ _argName = PathSegment str
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, _argType = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy (RequiredArgument mods a)) }
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instance
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(KnownSymbol sym, HasForeignType lang ftype [a], HasForeign lang ftype api)
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=> HasForeign lang ftype (QueryParams sym a :> api) where
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type Foreign ftype (QueryParams sym a :> api) = Foreign ftype api
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foreignFor lang Proxy Proxy req =
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foreignFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy api) $
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req & reqUrl.queryStr <>~ [QueryArg arg List]
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where
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str = pack . symbolVal $ (Proxy :: Proxy sym)
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arg = Arg
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{ _argName = PathSegment str
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, _argType = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy [a]) }
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instance
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(KnownSymbol sym, HasForeignType lang ftype Bool, HasForeign lang ftype api)
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=> HasForeign lang ftype (QueryFlag sym :> api) where
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type Foreign ftype (QueryFlag sym :> api) = Foreign ftype api
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foreignFor lang ftype Proxy req =
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foreignFor lang ftype (Proxy :: Proxy api) $
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req & reqUrl.queryStr <>~ [QueryArg arg Flag]
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where
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str = pack . symbolVal $ (Proxy :: Proxy sym)
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arg = Arg
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{ _argName = PathSegment str
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, _argType = typeFor lang ftype (Proxy :: Proxy Bool) }
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instance
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(HasForeignType lang ftype (Maybe a), HasForeign lang ftype api)
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=> HasForeign lang ftype (Fragment a :> api) where
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type Foreign ftype (Fragment a :> api) = Foreign ftype api
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foreignFor lang Proxy Proxy req =
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foreignFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy api) $
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req & reqUrl . frag .~ Just argT
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where
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argT = typeFor lang (Proxy :: Proxy ftype) (Proxy :: Proxy (Maybe a))
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instance HasForeign lang ftype Raw where
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type Foreign ftype Raw = HTTP.Method -> Req ftype
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foreignFor _ Proxy Proxy req method =
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req & reqFuncName . _FunctionName %~ ((toLower $ decodeUtf8 method) :)
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& reqMethod .~ method
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instance (Elem JSON list, HasForeignType lang ftype a, HasForeign lang ftype api)
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=> HasForeign lang ftype (ReqBody' mods list a :> api) where
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type Foreign ftype (ReqBody' mods list a :> api) = Foreign ftype api
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foreignFor lang ftype Proxy req =
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foreignFor lang ftype (Proxy :: Proxy api) $
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req & reqBody .~ (Just $ typeFor lang ftype (Proxy :: Proxy a))
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instance
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( HasForeign lang ftype api
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) => HasForeign lang ftype (StreamBody' mods framing ctype a :> api)
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where
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type Foreign ftype (StreamBody' mods framing ctype a :> api) = Foreign ftype api
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foreignFor _lang Proxy Proxy _req = error "HasForeign @StreamBody"
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instance (KnownSymbol path, HasForeign lang ftype api)
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=> HasForeign lang ftype (path :> api) where
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type Foreign ftype (path :> api) = Foreign ftype api
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foreignFor lang ftype Proxy req =
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foreignFor lang ftype (Proxy :: Proxy api) $
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req & reqUrl . path <>~ [Segment (Static (PathSegment str))]
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& reqFuncName . _FunctionName %~ (++ [str])
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where
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str = pack . symbolVal $ (Proxy :: Proxy path)
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instance HasForeign lang ftype api
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=> HasForeign lang ftype (RemoteHost :> api) where
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type Foreign ftype (RemoteHost :> api) = Foreign ftype api
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foreignFor lang ftype Proxy req =
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foreignFor lang ftype (Proxy :: Proxy api) req
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instance HasForeign lang ftype api
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=> HasForeign lang ftype (IsSecure :> api) where
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type Foreign ftype (IsSecure :> api) = Foreign ftype api
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foreignFor lang ftype Proxy req =
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foreignFor lang ftype (Proxy :: Proxy api) req
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instance HasForeign lang ftype api => HasForeign lang ftype (Vault :> api) where
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type Foreign ftype (Vault :> api) = Foreign ftype api
|
||
|
||
foreignFor lang ftype Proxy req =
|
||
foreignFor lang ftype (Proxy :: Proxy api) req
|
||
|
||
instance HasForeign lang ftype api =>
|
||
HasForeign lang ftype (WithNamedContext name context api) where
|
||
|
||
type Foreign ftype (WithNamedContext name context api) = Foreign ftype api
|
||
|
||
foreignFor lang ftype Proxy = foreignFor lang ftype (Proxy :: Proxy api)
|
||
|
||
instance HasForeign lang ftype api =>
|
||
HasForeign lang ftype (WithResource res :> api) where
|
||
|
||
type Foreign ftype (WithResource res :> api) = Foreign ftype api
|
||
|
||
foreignFor lang ftype Proxy = foreignFor lang ftype (Proxy :: Proxy api)
|
||
|
||
instance HasForeign lang ftype api
|
||
=> HasForeign lang ftype (HttpVersion :> api) where
|
||
type Foreign ftype (HttpVersion :> api) = Foreign ftype api
|
||
|
||
foreignFor lang ftype Proxy req =
|
||
foreignFor lang ftype (Proxy :: Proxy api) req
|
||
|
||
instance HasForeign lang ftype api
|
||
=> HasForeign lang ftype (Summary desc :> api) where
|
||
type Foreign ftype (Summary desc :> api) = Foreign ftype api
|
||
|
||
foreignFor lang ftype Proxy req =
|
||
foreignFor lang ftype (Proxy :: Proxy api) req
|
||
|
||
instance HasForeign lang ftype api
|
||
=> HasForeign lang ftype (Description desc :> api) where
|
||
type Foreign ftype (Description desc :> api) = Foreign ftype api
|
||
|
||
foreignFor lang ftype Proxy req =
|
||
foreignFor lang ftype (Proxy :: Proxy api) req
|
||
|
||
-- | Utility class used by 'listFromAPI' which computes
|
||
-- the data needed to generate a function for each endpoint
|
||
-- and hands it all back in a list.
|
||
class GenerateList ftype reqs where
|
||
generateList :: reqs -> [Req ftype]
|
||
|
||
instance GenerateList ftype EmptyForeignAPI where
|
||
generateList _ = []
|
||
|
||
instance GenerateList ftype (Req ftype) where
|
||
generateList r = [r]
|
||
|
||
instance (GenerateList ftype start, GenerateList ftype rest)
|
||
=> GenerateList ftype (start :<|> rest) where
|
||
generateList (start :<|> rest) = (generateList start) ++ (generateList rest)
|
||
|
||
-- | Generate the necessary data for codegen as a list, each 'Req'
|
||
-- describing one endpoint from your API type.
|
||
listFromAPI
|
||
:: (HasForeign lang ftype api, GenerateList ftype (Foreign ftype api))
|
||
=> Proxy lang
|
||
-> Proxy ftype
|
||
-> Proxy api
|
||
-> [Req ftype]
|
||
listFromAPI lang ftype p = generateList (foreignFor lang ftype p defReq)
|