git.iko.soy/typeable/servant
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Merge pull request #23 from haskell-servant/canonical-types
3311cbdAlp Mestanogullari
CHANGELOG.md+1
compare with master
unifiedsplit
@@ -1,5 +1,6 @@
10.3
10.3
2---
2---
3+* Add a `Canonicalize` type family that distributes all `:>`s inside `:<|>`s to get to the canonical type of an API -- which is then used in all other packages to avoid weird handler types in *servant-server*.
3* Multiple content-type/accept support for all the relevant combinators
4* Multiple content-type/accept support for all the relevant combinators
4* Provide *JSON*, *PlainText*, *OctetStream* and *FormUrlEncoded* content types out of the box
5* Provide *JSON*, *PlainText*, *OctetStream* and *FormUrlEncoded* content types out of the box
5* Type-safe link generation to API endpoints
6* Type-safe link generation to API endpoints
src/Servant/API.hs+39
@@ -1,3 +1,6 @@
1+{-# LANGUAGE TypeFamilies #-}
2+{-# LANGUAGE TypeOperators #-}
3+{-# LANGUAGE UndecidableInstances #-}
1module Servant.API (
4module Servant.API (
2
5
3 -- * Combinators
6 -- * Combinators
@@ -43,11 +46,16 @@ module Servant.API (
43 module Servant.Common.Text,
46 module Servant.Common.Text,
44 -- | Classes and instances for types that can be converted to and from @Text@
47 -- | Classes and instances for types that can be converted to and from @Text@
45
48
49+ -- * Canonicalizing (flattening) API types
50+ Canonicalize,
51+ canonicalize,
52+
46 -- * Utilities
53 -- * Utilities
47 module Servant.Utils.Links,
54 module Servant.Utils.Links,
48 -- | Type-safe internal URIs
55 -- | Type-safe internal URIs
49 ) where
56 ) where
50
57
58+import Data.Proxy (Proxy(..))
51import Servant.Common.Text (FromText(..), ToText(..))
59import Servant.Common.Text (FromText(..), ToText(..))
52import Servant.API.Alternative ((:<|>) (..))
60import Servant.API.Alternative ((:<|>) (..))
53import Servant.API.Capture (Capture)
61import Servant.API.Capture (Capture)
@@ -69,3 +77,34 @@ import Servant.API.ReqBody (ReqBody)
69import Servant.API.Sub ((:>))
77import Servant.API.Sub ((:>))
70import Servant.Utils.Links (HasLink (..), IsElem, IsElem',
78import Servant.Utils.Links (HasLink (..), IsElem, IsElem',
71 URI (..), safeLink)
79 URI (..), safeLink)
80+
81+-- | Turn an API type into its canonical form.
82+--
83+-- The canonical form of an API type is basically the all-flattened form
84+-- of the original type. More formally, it takes a type as input and hands you
85+-- back an /equivalent/ type formed of toplevel `:<|>`-separated chains of `:>`s,
86+-- i.e with all `:>`s distributed inside the `:<|>`s.
87+--
88+-- It basically turns:
89+--
90+-- > "hello" :> (Get Hello :<|> ReqBody Hello :> Put Hello)
91+--
92+-- into
93+--
94+-- > ("hello" :> Get Hello) :<|> ("hello" :> ReqBody Hello :> Put Hello)
95+--
96+-- i.e distributing all ':>'-separated bits into the subsequent ':<|>'s.
97+type family Canonicalize api :: * where
98+ -- requires UndecidableInstances
99+ Canonicalize (a :> (b :<|> c)) = a :> Canonicalize b :<|> a :> Canonicalize c
100+ Canonicalize ((a :<|> b) :> c) = a :> Canonicalize c :<|> b :> Canonicalize c
101+ Canonicalize (a :> b) = Redex b (Canonicalize b) a
102+ Canonicalize (a :<|> b) = Canonicalize a :<|> Canonicalize b
103+ Canonicalize a = a
104+
105+type family Redex a b c :: * where
106+ Redex a a first = Canonicalize first :> a
107+ Redex a b first = Canonicalize (first :> b)
108+
109+canonicalize :: Proxy layout -> Proxy (Canonicalize layout)
110+canonicalize Proxy = Proxy
src/Servant/API/ContentTypes.hs+2
@@ -55,6 +55,8 @@ module Servant.API.ContentTypes
55 , AcceptHeader(..)
55 , AcceptHeader(..)
56 , AllCTRender(..)
56 , AllCTRender(..)
57 , AllCTUnrender(..)
57 , AllCTUnrender(..)
58+ , AllMimeRender(..)
59+ , AllMimeUnrender(..)
58 , FromFormUrlEncoded(..)
60 , FromFormUrlEncoded(..)
59 , ToFormUrlEncoded(..)
61 , ToFormUrlEncoded(..)
60 , IsNonEmpty
62 , IsNonEmpty