Explicit ignore

This commit is contained in:
Julian K. Arni 2016-01-27 22:26:59 +01:00
parent f99d423442
commit ef2a44d11f
5 changed files with 30 additions and 30 deletions

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@ -88,7 +88,7 @@ them amounts to `/`-separating them in a URL.
These 5 combinators are very similar except that they each describe a
different HTTP method. This is how they're declared
``` haskell
``` haskell ignore
data Delete (contentTypes :: [*]) a
data Get (contentTypes :: [*]) a
data Patch (contentTypes :: [*]) a
@ -116,7 +116,7 @@ The `Capture` combinator in servant takes a (type-level) string representing
the "name of the variable" and a type, which indicates the type we want to
decode the "captured value" to.
``` haskell
``` haskell ignore
data Capture (s :: Symbol) a
-- s :: Symbol just says that 's' must be a type-level string.
```
@ -153,7 +153,7 @@ active users whereas `/users` would list them all.
Here are the corresponding data type declarations:
``` haskell
``` haskell ignore
data QueryParam (sym :: Symbol) a
data QueryParams (sym :: Symbol) a
data QueryFlag (sym :: Symbol)
@ -171,7 +171,7 @@ after *January 1st, 2005*.
Corresponding data type declarations below.
``` haskell
``` haskell ignore
data MatrixParam (sym :: Symbol) a
data MatrixParams (sym :: Symbol) a
data MatrixFlag (sym :: Symbol)
@ -206,7 +206,7 @@ Request` or `Unsupported Content Type` as appropriate.
Here's the data type declaration for it:
``` haskell
``` haskell ignore
data ReqBody (contentTypes :: [*]) a
```
@ -235,7 +235,7 @@ The `Header` combinator in servant takes a type-level string for the header
name and the type to which we want to decode the header's value (from some
textual representation), as illustrated below:
``` haskell
``` haskell ignore
data Header (sym :: Symbol) a
```
@ -274,7 +274,7 @@ headers too. *servant* provides a `Headers` combinator that carries a list of
`Header` and can be used by simply wrapping the "return type" of an endpoint
with it.
``` haskell
``` haskell ignore
data Headers (ls :: [*]) a
```

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@ -83,7 +83,7 @@ Each function makes available as an argument any value that the response may dep
As you can see in the code above, we just "pattern match our way" to these functions. If we try to derive less or more functions than there are endpoints in the API, we obviously get an error. The `BaseUrl` value there is just:
``` haskell
``` haskell ignore
-- | URI scheme to use
data Scheme =
Http -- ^ http://

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@ -26,5 +26,5 @@ convert =
go :: [String] -> [String]
go (a : r)
| ">" `isPrefixOf` a
= "``` haskell" : map (drop 2) (a : r) ++ "```" : []
= "``` haskell ignore" : map (drop 2) (a : r) ++ "```" : []
go x = x

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@ -94,7 +94,7 @@ With all of this, we can derive docs for our API.
*servant*'s markdown pretty printer is a function named `markdown`.
``` haskell
``` haskell ignore
markdown :: API -> String
```

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@ -68,7 +68,7 @@ need to have some language extensions and imports:
> import qualified Data.Aeson.Parser
> import qualified Text.Blaze.Html
``` haskell
``` haskell ignore
{-# LANGUAGE TypeFamilies #-}
```
@ -107,7 +107,7 @@ Nothing funny going on here. But we now can define our list of two users.
Let's also write our API type.
``` haskell
``` haskell ignore
type UserAPI1 = "users" :> Get '[JSON] [User]
```
@ -324,7 +324,7 @@ decided to provide a pair of typeclasses, `FromText` and `ToText` which just
let you say that you can respectively *extract* or *encode* values of some type
*from*/*to* text. Here are the definitions:
``` haskell
``` haskell ignore
class FromText a where
fromText :: Text -> Maybe a
@ -363,7 +363,7 @@ your own.
or writing the instances by hand:
``` haskell
``` haskell ignore
instance FromText UserId where
fromText = fmap UserId fromText
@ -394,7 +394,7 @@ The truth behind `JSON`
What exactly is `JSON`? Like the 3 other content types provided out of the box
by *servant*, it's a really dumb data type.
``` haskell
``` haskell ignore
data JSON
data PlainText
data FormUrlEncoded
@ -415,7 +415,7 @@ haddocks from this link, you can see that we just have to specify
use `(//) :: ByteString -> ByteString -> MediaType`. The precise way to specify
the `MediaType` is to write an instance for the `Accept` class:
``` haskell
``` haskell ignore
-- for reference:
class Accept ctype where
contentType :: Proxy ctype -> MediaType
@ -428,7 +428,7 @@ The second step is centered around the `MimeRender` and `MimeUnrender` classes.
These classes just let you specify a way to respectively encode and decode
values respectively into or from your content-type's representation.
``` haskell
``` haskell ignore
class Accept ctype => MimeRender ctype a where
mimeRender :: Proxy ctype -> a -> ByteString
-- alternatively readable as:
@ -442,7 +442,7 @@ In the case of `JSON`, this is easily dealt with! For any type `a` with a
`ToJSON` instance, we can render values of that type to JSON using
`Data.Aeson.encode`.
``` haskell
``` haskell ignore
instance ToJSON a => MimeRender JSON a where
mimeRender _ = encode
```
@ -450,7 +450,7 @@ instance ToJSON a => MimeRender JSON a where
And now the `MimeUnrender` class, which lets us extract values from lazy
`ByteString`s, alternatively failing with an error string.
``` haskell
``` haskell ignore
class Accept ctype => MimeUnrender ctype a where
mimeUnrender :: Proxy ctype -> ByteString -> Either String a
-- alternatively:
@ -471,7 +471,7 @@ you are curious.
This function is exactly what we need for our `MimeUnrender` instance.
``` haskell
``` haskell ignore
instance FromJSON a => MimeUnrender JSON a where
mimeUnrender _ = eitherDecodeLenient
```
@ -627,7 +627,7 @@ as interfaces to databases that we interact with in `IO`;
Let's recall some definitions.
``` haskell
``` haskell ignore
-- from the Prelude
data Either e a = Left e | Right a
@ -644,7 +644,7 @@ action that either returns an error or a result.
The aforementioned `either` package is worth taking a look at. Perhaps most
importantly:
``` haskell
``` haskell ignore
left :: Monad m => e -> EitherT e m a
```
Allows you to return an error from your handler (whereas `return` is enough to
@ -659,7 +659,7 @@ Performing IO
Another important instance from the list above is `MonadIO m => MonadIO (EitherT e m)`. [`MonadIO`](http://hackage.haskell.org/package/transformers-0.4.3.0/docs/Control-Monad-IO-Class.html) is a class from the *transformers* package defined as:
``` haskell
``` haskell ignore
class Monad m => MonadIO m where
liftIO :: IO a -> m a
```
@ -688,7 +688,7 @@ error message, all you have to do is use the `left` function mentioned above
and provide it with the appropriate value of type `ServantErr`, which is
defined as:
``` haskell
``` haskell ignore
data ServantErr = ServantErr
{ errHTTPCode :: Int
, errReasonPhrase :: String
@ -773,7 +773,7 @@ under some path in your web API. As mentioned earlier in this document, the
application". Well, servant-server provides a function to get a file and
directory serving WAI application, namely:
``` haskell
``` haskell ignore
-- exported by Servant and Servant.Server
serveDirectory :: FilePath -> Server Raw
```
@ -809,7 +809,7 @@ In other words:
Here is our little server in action.
``` haskell
``` haskell ignore
$ curl http://localhost:8081/code/T1.hs
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeFamilies #-}
@ -918,7 +918,7 @@ We can instead factor out the `userid`:
However, you have to be aware that this has an effect on the type of the corresponding `Server`:
``` haskell
``` haskell ignore
Server UserAPI3 = (Int -> EitherT ServantErr IO User)
:<|> (Int -> EitherT ServantErr IO ())
@ -1076,7 +1076,7 @@ Using another monad for your handlers
Remember how `Server` turns combinators for HTTP methods into `EitherT ServantErr IO`? Well, actually, there's more to that. `Server` is actually a simple type synonym.
``` haskell
``` haskell ignore
type Server api = ServerT api (EitherT ServantErr IO)
```
@ -1090,7 +1090,7 @@ Natural transformations
If we have a function that gets us from an `m a` to an `n a`, for any `a`, what
do we have?
``` haskell
``` haskell ignore
newtype m :~> n = Nat { unNat :: forall a. m a -> n a}
-- For example
@ -1103,7 +1103,7 @@ So if you want to write handlers using another monad/type than `EitherT
ServantErr IO`, say the `Reader String` monad, the first thing you have to
prepare is a function:
``` haskell
``` haskell ignore
readerToEither :: Reader String :~> EitherT ServantErr IO
```