Yesod.Core

Type classes

class RenderRoute site => Yesod site where

Define settings for a Yesod applications. All methods have intelligent defaults, and therefore no implementation is required.

Minimal complete definition

Nothing

Methods

approot :: Approot site

An absolute URL to the root of the application. Do not include trailing slash.

Default value: guessApproot. If you know your application root statically, it will be more efficient and more reliable to instead use ApprootStatic or ApprootMaster. If you do not need full absolute URLs, you can use ApprootRelative instead.

Note: Prior to yesod-core 1.5, the default value was ApprootRelative.

catchHandlerExceptions :: MonadUnliftIO m => site -> m a -> (SomeException -> m a) -> m a

allows the user to specify how exceptions are cought. by default all async exceptions are thrown and synchronous exceptions render a 500 page. To catch all exceptions (even async) to render a 500 page, set this to catchSyncOrAsync. Beware this may have negative effects with functions like timeout.

Since: 1.6.24.0

errorHandler :: ErrorResponse -> HandlerFor site TypedContent

Output error response pages.

Default value: defaultErrorHandler.

defaultLayout :: WidgetFor site () -> HandlerFor site Html

Applies some form of layout to the contents of a page.

urlParamRenderOverride

Arguments

:: site

-> Route site

-> [(Text, Text)]

query string

-> Maybe Builder

Override the rendering function for a particular URL and query string parameters. One use case for this is to offload static hosting to a different domain name to avoid sending cookies.

For backward compatibility default implementation is in terms of urlRenderOverride, probably ineffective

Since 1.4.23

isAuthorized

Arguments

:: Route site

-> Bool

is this a write request?

-> HandlerFor site AuthResult

Determine if a request is authorized or not.

Return Authorized if the request is authorized, Unauthorized a message if unauthorized. If authentication is required, return AuthenticationRequired.

isWriteRequest :: Route site -> HandlerFor site Bool

Determines whether the current request is a write request. By default, this assumes you are following RESTful principles, and determines this from request method. In particular, all except the following request methods are considered write: GET HEAD OPTIONS TRACE.

This function is used to determine if a request is authorized; see isAuthorized.

authRoute :: site -> Maybe (Route site)

The default route for authentication.

Used in particular by isAuthorized, but library users can do whatever they want with it.

cleanPath :: site -> [Text] -> Either [Text] [Text]

A function used to clean up path segments. It returns Right with a clean path or Left with a new set of pieces the user should be redirected to. The default implementation enforces:

• No double slashes
• There is no trailing slash.

Note that versions of Yesod prior to 0.7 used a different set of rules involing trailing slashes.

joinPath

Arguments

:: site

-> Text

application root

-> [Text]

path pieces

-> [(Text, Text)]

query string

-> Builder

Builds an absolute URL by concatenating the application root with the pieces of a path and a query string, if any. Note that the pieces of the path have been previously cleaned up by cleanPath.

addStaticContent

Arguments

:: Text

filename extension

-> Text

mime-type

-> ByteString

content

-> HandlerFor site (Maybe (Either Text (Route site, [(Text, Text)])))

This function is used to store some static content to be served as an external file. The most common case of this is stashing CSS and JavaScript content in an external file; the Yesod.Widget module uses this feature.

The return value is Nothing if no storing was performed; this is the default implementation. A Just Left gives the absolute URL of the file, whereas a Just Right gives the type-safe URL. The former is necessary when you are serving the content outside the context of a Yesod application, such as via memcached.

maximumContentLength :: site -> Maybe (Route site) -> Maybe Word64

Maximum allowed length of the request body, in bytes. This method may be ignored if maximumContentLengthIO is overridden.

If Nothing, no maximum is applied.

Default: 2 megabytes.

maximumContentLengthIO :: site -> Maybe (Route site) -> IO (Maybe Word64)

Maximum allowed length of the request body, in bytes. This is similar to maximumContentLength, but the result lives in IO. This allows you to dynamically change the maximum file size based on some external source like a database or an IORef.

The default implementation uses maximumContentLength. Future version of yesod will remove maximumContentLength and use this method exclusively.

Since: 1.6.13

makeLogger :: site -> IO Logger

Creates a Logger to use for log messages.

Note that a common technique (endorsed by the scaffolding) is to create a Logger value and place it in your foundation datatype, and have this method return that already created value. That way, you can use that same Logger for printing messages during app initialization.

Default: the defaultMakeLogger function.

messageLoggerSource

Arguments

:: site

-> Logger

-> Loc

position in source code

-> LogSource

-> LogLevel

-> LogStr

message

-> IO ()

Send a message to the Logger provided by getLogger.

Default: the defaultMessageLoggerSource function, using shouldLogIO to check whether we should log.

jsLoader :: site -> ScriptLoadPosition site

Where to Load sripts from. We recommend the default value, BottomOfBody.

jsAttributes :: site -> [(Text, Text)]

Default attributes to put on the JavaScript script tag generated for julius files

jsAttributesHandler :: HandlerFor site [(Text, Text)]

Same as jsAttributes but allows you to run arbitrary Handler code

This is useful if you need to add a randomised nonce value to the script tag generated by widgetFile. If this function is overridden then jsAttributes is ignored.

Since: 1.6.16

makeSessionBackend :: site -> IO (Maybe SessionBackend)

Create a session backend. Returning Nothing disables sessions. If you'd like to change the way that the session cookies are created, take a look at customizeSessionCookies.

Default: Uses clientsession with a 2 hour timeout.

fileUpload :: site -> RequestBodyLength -> FileUpload

How to store uploaded files.

Default: When the request body is greater than 50kb, store in a temp file. For chunked request bodies, store in a temp file. Otherwise, store in memory.

shouldLogIO :: site -> LogSource -> LogLevel -> IO Bool

Should we log the given log source/level combination.

Default: the defaultShouldLogIO function.

Since 1.2.4

yesodMiddleware :: ToTypedContent res => HandlerFor site res -> HandlerFor site res

A Yesod middleware, which will wrap every handler function. This allows you to run code before and after a normal handler.

Default: the defaultYesodMiddleware function.

Since: 1.1.6

yesodWithInternalState :: site -> Maybe (Route site) -> (InternalState -> IO a) -> IO a

How to allocate an InternalState for each request.

The default implementation is almost always what you want. However, if you know that you are never taking advantage of the MonadResource instance in your handler functions, setting this to a dummy implementation can provide a small optimization. Only do this if you really know what you're doing, otherwise you can turn safe code into a runtime error!

Since 1.4.2

defaultMessageWidget :: Html -> HtmlUrl (Route site) -> WidgetFor site ()

Convert a title and HTML snippet into a Widget. Used primarily for wrapping up error messages for better display.

Since: 1.4.30

Instances

Yesod LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

approot :: Approot LiteApp

catchHandlerExceptions :: MonadUnliftIO m => LiteApp -> m a -> (SomeException -> m a) -> m a

errorHandler :: ErrorResponse -> HandlerFor LiteApp TypedContent

defaultLayout :: WidgetFor LiteApp () -> HandlerFor LiteApp Html

urlParamRenderOverride :: LiteApp -> Route LiteApp -> [(Text, Text)] -> Maybe Builder

isAuthorized :: Route LiteApp -> Bool -> HandlerFor LiteApp AuthResult

isWriteRequest :: Route LiteApp -> HandlerFor LiteApp Bool

authRoute :: LiteApp -> Maybe (Route LiteApp)

cleanPath :: LiteApp -> [Text] -> Either [Text] [Text]

joinPath :: LiteApp -> Text -> [Text] -> [(Text, Text)] -> Builder

addStaticContent :: Text -> Text -> ByteString -> HandlerFor LiteApp (Maybe (Either Text (Route LiteApp, [(Text, Text)])))

maximumContentLength :: LiteApp -> Maybe (Route LiteApp) -> Maybe Word64

maximumContentLengthIO :: LiteApp -> Maybe (Route LiteApp) -> IO (Maybe Word64)

makeLogger :: LiteApp -> IO Logger

messageLoggerSource :: LiteApp -> Logger -> Loc -> LogSource -> LogLevel -> LogStr -> IO ()

jsLoader :: LiteApp -> ScriptLoadPosition LiteApp

jsAttributes :: LiteApp -> [(Text, Text)]

jsAttributesHandler :: HandlerFor LiteApp [(Text, Text)]

makeSessionBackend :: LiteApp -> IO (Maybe SessionBackend)

fileUpload :: LiteApp -> RequestBodyLength -> FileUpload

shouldLogIO :: LiteApp -> LogSource -> LogLevel -> IO Bool

yesodMiddleware :: ToTypedContent res => HandlerFor LiteApp res -> HandlerFor LiteApp res

yesodWithInternalState :: LiteApp -> Maybe (Route LiteApp) -> (InternalState -> IO a) -> IO a

defaultMessageWidget :: Html -> HtmlUrl (Route LiteApp) -> WidgetFor LiteApp ()

class Yesod site => YesodDispatch site where

This class is automatically instantiated when you use the template haskell mkYesod function. You should never need to deal with it directly.

Methods

yesodDispatch :: YesodRunnerEnv site -> Application

Instances

YesodDispatch LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

yesodDispatch :: YesodRunnerEnv LiteApp -> Application

class YesodSubDispatch sub master where

Methods

yesodSubDispatch :: YesodSubRunnerEnv sub master -> Application

Instances

YesodSubDispatch WaiSubsite master

Defined in Yesod.Core.Class.Dispatch

Methods

yesodSubDispatch :: YesodSubRunnerEnv WaiSubsite master -> Application

YesodSubDispatch WaiSubsiteWithAuth master

Defined in Yesod.Core.Class.Dispatch

Methods

yesodSubDispatch :: YesodSubRunnerEnv WaiSubsiteWithAuth master -> Application

class Eq (Route a) => RenderRoute a where

Associated Types

data Route a

The type-safe URLs associated with a site argument.

Methods

renderRoute

Arguments

:: Route a

-> ([Text], [(Text, Text)])

The path of the URL split on forward slashes, and a list of query parameters with their associated value.

Instances

RenderRoute LiteApp

Defined in Yesod.Core.Internal.LiteApp

Associated Types

data Route LiteApp

Methods

renderRoute :: Route LiteApp -> ([Text], [(Text, Text)])

RenderRoute WaiSubsite

Defined in Yesod.Core.Types

Associated Types

data Route WaiSubsite

Methods

renderRoute :: Route WaiSubsite -> ([Text], [(Text, Text)])

RenderRoute WaiSubsiteWithAuth

Defined in Yesod.Core.Types

Associated Types

data Route WaiSubsiteWithAuth

Methods

renderRoute :: Route WaiSubsiteWithAuth -> ([Text], [(Text, Text)])

class RenderRoute a => ParseRoute a where

Methods

parseRoute

Arguments

:: ([Text], [(Text, Text)])

The path of the URL split on forward slashes, and a list of query parameters with their associated value.

-> Maybe (Route a)

Instances

ParseRoute LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

parseRoute :: ([Text], [(Text, Text)]) -> Maybe (Route LiteApp)

ParseRoute WaiSubsite

Defined in Yesod.Core.Types

Methods

parseRoute :: ([Text], [(Text, Text)]) -> Maybe (Route WaiSubsite)

ParseRoute WaiSubsiteWithAuth

Defined in Yesod.Core.Types

Methods

parseRoute :: ([Text], [(Text, Text)]) -> Maybe (Route WaiSubsiteWithAuth)

class RenderRoute a => RouteAttrs a where

Methods

routeAttrs

Arguments

:: Route a

-> Set Text

A set of attributes associated with the route.

Breadcrumbs

class YesodBreadcrumbs site where

A type-safe, concise method of creating breadcrumbs for pages. For each resource, you declare the title of the page and the parent resource (if present).

Methods

breadcrumb :: Route site -> HandlerFor site (Text, Maybe (Route site))

Returns the title and the parent resource, if available. If you return a Nothing, then this is considered a top-level page.

breadcrumbs :: (YesodBreadcrumbs site, Show (Route site), Eq (Route site)) => HandlerFor site (Text, [(Route site, Text)])

Gets the title of the current page and the hierarchy of parent pages, along with their respective titles.

Types

data Approot master

How to determine the root of the application for constructing URLs.

Note that future versions of Yesod may add new constructors without bumping the major version number. As a result, you should not pattern match on Approot values.

Constructors

ApprootRelative

No application root.

ApprootStatic !Text

ApprootMaster !(master -> Text)

ApprootRequest !(master -> Request -> Text)

data FileUpload

Constructors

FileUploadMemory !(BackEnd ByteString)

FileUploadDisk !(InternalState -> BackEnd FilePath)

FileUploadSource !(BackEnd (ConduitT () ByteString (ResourceT IO) ()))

data ErrorResponse

Responses to indicate some form of an error occurred.

Constructors

NotFound

The requested resource was not found. Examples of when this occurs include when an incorrect URL is used, or yesod-persistent's get404 doesn't find a value. HTTP status: 404.

InternalError !Text

Some sort of unexpected exception. If your application uses throwIO or error to throw an exception, this is the form it would take. HTTP status: 500.

InvalidArgs ![Text]

Indicates some sort of invalid or missing argument, like a missing query parameter or malformed JSON body. Examples Yesod functions that send this include requireCheckJsonBody and Yesod.Auth.GoogleEmail2. HTTP status: 400.

NotAuthenticated

Indicates the user is not logged in. This is thrown when isAuthorized returns AuthenticationRequired. HTTP code: 401.

PermissionDenied !Text

Indicates the user doesn't have permission to access the requested resource. This is thrown when isAuthorized returns Unauthorized. HTTP code: 403.

BadMethod !Method

Indicates the URL would have been valid if used with a different HTTP method (e.g. a GET was used, but only POST is handled.) HTTP code: 405.

Instances

Generic ErrorResponse

Defined in Yesod.Core.Types

Associated Types

type Rep ErrorResponse :: Type -> Type

Methods

from :: ErrorResponse -> Rep ErrorResponse x

to :: Rep ErrorResponse x -> ErrorResponse

Show ErrorResponse

Defined in Yesod.Core.Types

Methods

showsPrec :: Int -> ErrorResponse -> ShowS

show :: ErrorResponse -> String

showList :: [ErrorResponse] -> ShowS

NFData ErrorResponse

Defined in Yesod.Core.Types

Methods

rnf :: ErrorResponse -> ()

Eq ErrorResponse

Defined in Yesod.Core.Types

Methods

(==) :: ErrorResponse -> ErrorResponse -> Bool

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

type Rep ErrorResponse

Defined in Yesod.Core.Types

type Rep ErrorResponse = D1 ('MetaData "ErrorResponse" "Yesod.Core.Types" "yesod-core-1.6.25.0-858t43E66FKJnR2oRqq3Fn" 'False) ((C1 ('MetaCons "NotFound" 'PrefixI 'False) (U1 :: Type -> Type) :+: (C1 ('MetaCons "InternalError" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Text)) :+: C1 ('MetaCons "InvalidArgs" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 [Text])))) :+: (C1 ('MetaCons "NotAuthenticated" 'PrefixI 'False) (U1 :: Type -> Type) :+: (C1 ('MetaCons "PermissionDenied" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Text)) :+: C1 ('MetaCons "BadMethod" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Method)))))

Utilities

maybeAuthorized

Arguments

:: Yesod site

=> Route site

-> Bool

is this a write request?

-> HandlerT site IO (Maybe (Route site))

Return the same URL if the user is authorized to see it.

Built on top of isAuthorized. This is useful for building page that only contain links to pages the user is allowed to see.

widgetToPageContent :: Yesod site => WidgetFor site () -> HandlerFor site (PageContent (Route site))

Convert a widget to a PageContent.

Defaults

defaultErrorHandler :: Yesod site => ErrorResponse -> HandlerFor site TypedContent

The default error handler for errorHandler.

defaultYesodMiddleware :: Yesod site => HandlerFor site res -> HandlerFor site res

Default implementation of yesodMiddleware. Adds the response header "Vary: Accept, Accept-Language", "X-XSS-Protection: 1; mode=block", and performs authorization checks.

Since 1.2.0

authorizationCheck :: Yesod site => HandlerFor site ()

Check if a given request is authorized via isAuthorized and isWriteRequest.

Since 1.2.0

Data types

data AuthResult

Constructors

Authorized

AuthenticationRequired

Unauthorized !Text

Instances

Read AuthResult

Defined in Yesod.Core.Types

Methods

readsPrec :: Int -> ReadS AuthResult

readList :: ReadS [AuthResult]

readPrec :: ReadPrec AuthResult

readListPrec :: ReadPrec [AuthResult]

Show AuthResult

Defined in Yesod.Core.Types

Methods

showsPrec :: Int -> AuthResult -> ShowS

show :: AuthResult -> String

showList :: [AuthResult] -> ShowS

Eq AuthResult

Defined in Yesod.Core.Types

Methods

(==) :: AuthResult -> AuthResult -> Bool

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

unauthorizedI :: (MonadHandler m, RenderMessage (HandlerSite m) msg) => msg -> m AuthResult

Return an Unauthorized value, with the given i18n message.

Logging

defaultMakeLogger :: IO Logger

Default implementation of makeLogger. Sends to stdout and automatically flushes on each write.

Since 1.4.10

defaultMessageLoggerSource

Arguments

:: (LogSource -> LogLevel -> IO Bool)

Check whether we should log this

-> Logger

-> Loc

position in source code

-> LogSource

-> LogLevel

-> LogStr

message

-> IO ()

Default implementation of messageLoggerSource. Checks if the message should be logged using the provided function, and if so, formats using formatLogMessage. You can use defaultShouldLogIO as the provided function.

Since 1.4.10

defaultShouldLogIO :: LogSource -> LogLevel -> IO Bool

Default implementation of shouldLog. Logs everything at or above LevelInfo.

Since 1.4.10

formatLogMessage

Arguments

:: IO ZonedDate

-> Loc

-> LogSource

-> LogLevel

-> LogStr

message

-> IO LogStr

Default formatting for log messages. When you use the template haskell logging functions for to log with information about the source location, that information will be appended to the end of the log. When you use the non-TH logging functions, like logDebugN, this function does not include source information. This currently works by checking to see if the package name is the string "<unknown>". This is a hack, but it removes some of the visual clutter from non-TH logs.

Since 1.4.10

data LogLevel

Constructors

LevelDebug

LevelInfo

LevelWarn

LevelError

LevelOther Text

Instances

Read LogLevel

Defined in Control.Monad.Logger

Methods

readsPrec :: Int -> ReadS LogLevel

readList :: ReadS [LogLevel]

readPrec :: ReadPrec LogLevel

readListPrec :: ReadPrec [LogLevel]

Show LogLevel

Defined in Control.Monad.Logger

Methods

showsPrec :: Int -> LogLevel -> ShowS

show :: LogLevel -> String

showList :: [LogLevel] -> ShowS

Eq LogLevel

Defined in Control.Monad.Logger

Methods

(==) :: LogLevel -> LogLevel -> Bool

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

Ord LogLevel

Defined in Control.Monad.Logger

Methods

compare :: LogLevel -> LogLevel -> Ordering

(<) :: LogLevel -> LogLevel -> Bool

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

(>) :: LogLevel -> LogLevel -> Bool

(>=) :: LogLevel -> LogLevel -> Bool

max :: LogLevel -> LogLevel -> LogLevel

min :: LogLevel -> LogLevel -> LogLevel

Lift LogLevel

Defined in Control.Monad.Logger

Methods

lift :: Quote m => LogLevel -> m Exp

liftTyped :: forall (m :: Type -> Type). Quote m => LogLevel -> Code m LogLevel

logDebug :: Q Exp

Generates a function that takes a Text and logs a LevelDebug message. Usage:

$(logDebug) "This is a debug log message"

logInfo :: Q Exp

See logDebug

logWarn :: Q Exp

See logDebug

logError :: Q Exp

See logDebug

logOther :: Text -> Q Exp

Generates a function that takes a Text and logs a LevelOther message. Usage:

$(logOther "My new level") "This is a log message"

logDebugS :: Q Exp

Generates a function that takes a LogSource and Text and logs a LevelDebug message. Usage:

$logDebugS "SomeSource" "This is a debug log message"

logInfoS :: Q Exp

See logDebugS

logWarnS :: Q Exp

See logDebugS

logErrorS :: Q Exp

See logDebugS

logOtherS :: Q Exp

Generates a function that takes a LogSource, a level name and a Text and logs a LevelOther message. Usage:

$logOtherS "SomeSource" "My new level" "This is a log message"

Sessions

newtype SessionBackend

Constructors

SessionBackend

Fields

• sbLoadSession :: Request -> IO (SessionMap, SaveSession)

  Return the session data and a function to save the session

customizeSessionCookies :: (SetCookie -> SetCookie) -> SessionBackend -> SessionBackend

Customize the cookies used by the session backend. You may use this function on your definition of makeSessionBackend.

For example, you could set the cookie domain so that it would work across many subdomains:

makeSessionBackend site =
    (fmap . fmap) (customizeSessionCookies addDomain) ...
  where
    addDomain cookie = cookie { setCookieDomain = Just ".example.com" }

Default: Do not customize anything (id).

defaultClientSessionBackend

Arguments

:: Int

minutes

-> FilePath

key file

-> IO SessionBackend

envClientSessionBackend

Arguments

:: Int

minutes

-> String

environment variable name

-> IO SessionBackend

Create a SessionBackend which reads the session key from the named environment variable.

This can be useful if:

1. You can't rely on a persistent file system (e.g. Heroku)
2. Your application is open source (e.g. you can't commit the key)

By keeping a consistent value in the environment variable, your users will have consistent sessions without relying on the file system.

Note: A suitable value should only be obtained in one of two ways:

1. Run this code without the variable set, a value will be generated and printed on devstdout/
2. Use clientsession-generate

Since 1.4.5

clientSessionBackend

Arguments

:: Key

The encryption key

-> IO ClientSessionDateCache

See clientSessionDateCacher

-> SessionBackend

sslOnlySessions :: IO (Maybe SessionBackend) -> IO (Maybe SessionBackend)

Defends against session hijacking by setting the secure bit on session cookies so that browsers will not transmit them over http. With this setting on, it follows that the server will regard requests made over http as sessionless, because the session cookie will not be included in the request. Use this as part of a total security measure which also includes disabling HTTP traffic to the site or issuing redirects from HTTP urls, and composing sslOnlyMiddleware with the site's yesodMiddleware.

Since 1.4.7

laxSameSiteSessions :: IO (Maybe SessionBackend) -> IO (Maybe SessionBackend)

Helps defend against CSRF attacks by setting the SameSite attribute on session cookies to Lax. With the Lax setting, the cookie will be sent with same-site requests, and with cross-site top-level navigations.

This option is liable to change in future versions of Yesod as the spec evolves. View more information here.

Since: 1.4.23

strictSameSiteSessions :: IO (Maybe SessionBackend) -> IO (Maybe SessionBackend)

Helps defend against CSRF attacks by setting the SameSite attribute on session cookies to Strict. With the Strict setting, the cookie will only be sent with same-site requests.

This option is liable to change in future versions of Yesod as the spec evolves. View more information here.

Since: 1.4.23

sslOnlyMiddleware

Arguments

:: Int

minutes

-> HandlerFor site res

-> HandlerFor site res

Apply a Strict-Transport-Security header with the specified timeout to all responses so that browsers will rewrite all http links to https until the timeout expires. For security, the max-age of the STS header should always equal or exceed the client sessions timeout. This defends against SSL-stripping man-in-the-middle attacks. It is only effective if a secure connection has already been made; Strict-Transport-Security headers are ignored over HTTP.

Since 1.4.7

clientSessionDateCacher

Arguments

:: NominalDiffTime

Inactive session validity.

-> IO (IO ClientSessionDateCache, IO ())

loadClientSession

Arguments

:: Key

-> IO ClientSessionDateCache

See clientSessionDateCacher

-> ByteString

session name

-> Request

-> IO (SessionMap, SaveSession)

data Header

Headers to be added to a Result.

Constructors

AddCookie !SetCookie

DeleteCookie !ByteString !ByteString

name and path

Header !(CI ByteString) !ByteString

key and value

Instances

Show Header

Defined in Yesod.Core.Types

Methods

showsPrec :: Int -> Header -> ShowS

show :: Header -> String

showList :: [Header] -> ShowS

NFData Header

Defined in Yesod.Core.Types

Methods

rnf :: Header -> ()

Eq Header

Defined in Yesod.Core.Types

Methods

(==) :: Header -> Header -> Bool

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

CSRF protection

defaultCsrfMiddleware :: Yesod site => HandlerFor site res -> HandlerFor site res

Calls defaultCsrfSetCookieMiddleware and defaultCsrfCheckMiddleware.

For details, see the "AJAX CSRF protection" section of Yesod.Core.Handler.

You can chain this middleware together with other middleware like so:

yesodMiddleware = defaultYesodMiddleware . defaultCsrfMiddleware

or:

yesodMiddleware app = defaultYesodMiddleware $ defaultCsrfMiddleware $ app

Since 1.4.14

defaultCsrfSetCookieMiddleware :: HandlerFor site res -> HandlerFor site res

Calls csrfSetCookieMiddleware with the defaultCsrfCookieName.

The cookie's path is set to /, making it valid for your whole website.

Since 1.4.14

csrfSetCookieMiddleware :: HandlerFor site res -> SetCookie -> HandlerFor site res

Takes a SetCookie and overrides its value with a CSRF token, then sets the cookie. See setCsrfCookieWithCookie.

For details, see the "AJAX CSRF protection" section of Yesod.Core.Handler.

Make sure to set the setCookiePath to the root path of your application, otherwise you'll generate a new CSRF token for every path of your app. If your app is run from from e.g. www.example.com/app1, use app1. The vast majority of sites will just use /.

Since 1.4.14

defaultCsrfCheckMiddleware :: Yesod site => HandlerFor site res -> HandlerFor site res

Calls csrfCheckMiddleware with isWriteRequest, defaultCsrfHeaderName, and defaultCsrfParamName as parameters.

Since 1.4.14

csrfCheckMiddleware

Arguments

:: HandlerFor site res

-> HandlerFor site Bool

Whether or not to perform the CSRF check.

-> CI ByteString

The header name to lookup the CSRF token from.

-> Text

The POST parameter name to lookup the CSRF token from.

-> HandlerFor site res

Looks up the CSRF token from the request headers or POST parameters. If the value doesn't match the token stored in the session, this function throws a PermissionDenied error.

For details, see the "AJAX CSRF protection" section of Yesod.Core.Handler.

Since 1.4.14

JS loaders

data ScriptLoadPosition master

Constructors

BottomOfBody

BottomOfHeadBlocking

BottomOfHeadAsync !(BottomOfHeadAsync master)

type BottomOfHeadAsync master

Arguments

 = [Text]

urls to load asynchronously

-> Maybe (HtmlUrl (Route master))

widget of js to run on async completion

-> HtmlUrl (Route master)

widget to insert at the bottom of head

Generalizing type classes

class (MonadResource m, MonadLogger m) => MonadHandler m where

Associated Types

type HandlerSite m

type SubHandlerSite m

Methods

liftHandler :: HandlerFor (HandlerSite m) a -> m a

liftSubHandler :: SubHandlerFor (SubHandlerSite m) (HandlerSite m) a -> m a

Instances

MonadHandler m => MonadHandler (ListT m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (ListT m)

type SubHandlerSite (ListT m)

Methods

liftHandler :: HandlerFor (HandlerSite (ListT m)) a -> ListT m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (ListT m)) (HandlerSite (ListT m)) a -> ListT m a

MonadHandler m => MonadHandler (MaybeT m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (MaybeT m)

type SubHandlerSite (MaybeT m)

Methods

liftHandler :: HandlerFor (HandlerSite (MaybeT m)) a -> MaybeT m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (MaybeT m)) (HandlerSite (MaybeT m)) a -> MaybeT m a

MonadHandler (HandlerFor site)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (HandlerFor site)

type SubHandlerSite (HandlerFor site)

Methods

liftHandler :: HandlerFor (HandlerSite (HandlerFor site)) a -> HandlerFor site a

liftSubHandler :: SubHandlerFor (SubHandlerSite (HandlerFor site)) (HandlerSite (HandlerFor site)) a -> HandlerFor site a

MonadHandler (WidgetFor site)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (WidgetFor site)

type SubHandlerSite (WidgetFor site)

Methods

liftHandler :: HandlerFor (HandlerSite (WidgetFor site)) a -> WidgetFor site a

liftSubHandler :: SubHandlerFor (SubHandlerSite (WidgetFor site)) (HandlerSite (WidgetFor site)) a -> WidgetFor site a

MonadHandler m => MonadHandler (ExceptT e m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (ExceptT e m)

type SubHandlerSite (ExceptT e m)

Methods

liftHandler :: HandlerFor (HandlerSite (ExceptT e m)) a -> ExceptT e m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (ExceptT e m)) (HandlerSite (ExceptT e m)) a -> ExceptT e m a

MonadHandler m => MonadHandler (IdentityT m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (IdentityT m)

type SubHandlerSite (IdentityT m)

Methods

liftHandler :: HandlerFor (HandlerSite (IdentityT m)) a -> IdentityT m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (IdentityT m)) (HandlerSite (IdentityT m)) a -> IdentityT m a

MonadHandler m => MonadHandler (ReaderT r m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (ReaderT r m)

type SubHandlerSite (ReaderT r m)

Methods

liftHandler :: HandlerFor (HandlerSite (ReaderT r m)) a -> ReaderT r m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (ReaderT r m)) (HandlerSite (ReaderT r m)) a -> ReaderT r m a

MonadHandler m => MonadHandler (StateT s m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (StateT s m)

type SubHandlerSite (StateT s m)

Methods

liftHandler :: HandlerFor (HandlerSite (StateT s m)) a -> StateT s m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (StateT s m)) (HandlerSite (StateT s m)) a -> StateT s m a

MonadHandler m => MonadHandler (StateT s m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (StateT s m)

type SubHandlerSite (StateT s m)

Methods

liftHandler :: HandlerFor (HandlerSite (StateT s m)) a -> StateT s m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (StateT s m)) (HandlerSite (StateT s m)) a -> StateT s m a

(Monoid w, MonadHandler m) => MonadHandler (WriterT w m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (WriterT w m)

type SubHandlerSite (WriterT w m)

Methods

liftHandler :: HandlerFor (HandlerSite (WriterT w m)) a -> WriterT w m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (WriterT w m)) (HandlerSite (WriterT w m)) a -> WriterT w m a

(Monoid w, MonadHandler m) => MonadHandler (WriterT w m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (WriterT w m)

type SubHandlerSite (WriterT w m)

Methods

liftHandler :: HandlerFor (HandlerSite (WriterT w m)) a -> WriterT w m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (WriterT w m)) (HandlerSite (WriterT w m)) a -> WriterT w m a

MonadHandler (SubHandlerFor sub master)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (SubHandlerFor sub master)

type SubHandlerSite (SubHandlerFor sub master)

Methods

liftHandler :: HandlerFor (HandlerSite (SubHandlerFor sub master)) a -> SubHandlerFor sub master a

liftSubHandler :: SubHandlerFor (SubHandlerSite (SubHandlerFor sub master)) (HandlerSite (SubHandlerFor sub master)) a -> SubHandlerFor sub master a

MonadHandler m => MonadHandler (ConduitM i o m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (ConduitM i o m)

type SubHandlerSite (ConduitM i o m)

Methods

liftHandler :: HandlerFor (HandlerSite (ConduitM i o m)) a -> ConduitM i o m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (ConduitM i o m)) (HandlerSite (ConduitM i o m)) a -> ConduitM i o m a

(Monoid w, MonadHandler m) => MonadHandler (RWST r w s m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (RWST r w s m)

type SubHandlerSite (RWST r w s m)

Methods

liftHandler :: HandlerFor (HandlerSite (RWST r w s m)) a -> RWST r w s m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (RWST r w s m)) (HandlerSite (RWST r w s m)) a -> RWST r w s m a

(Monoid w, MonadHandler m) => MonadHandler (RWST r w s m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (RWST r w s m)

type SubHandlerSite (RWST r w s m)

Methods

liftHandler :: HandlerFor (HandlerSite (RWST r w s m)) a -> RWST r w s m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (RWST r w s m)) (HandlerSite (RWST r w s m)) a -> RWST r w s m a

MonadHandler m => MonadHandler (Pipe l i o u m)

Defined in Yesod.Core.Class.Handler

Associated Types

type HandlerSite (Pipe l i o u m)

type SubHandlerSite (Pipe l i o u m)

Methods

liftHandler :: HandlerFor (HandlerSite (Pipe l i o u m)) a -> Pipe l i o u m a

liftSubHandler :: SubHandlerFor (SubHandlerSite (Pipe l i o u m)) (HandlerSite (Pipe l i o u m)) a -> Pipe l i o u m a

class MonadHandler m => MonadWidget m where

Methods

liftWidget :: WidgetFor (HandlerSite m) a -> m a

Instances

MonadWidget m => MonadWidget (ListT m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (ListT m)) a -> ListT m a

MonadWidget m => MonadWidget (MaybeT m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (MaybeT m)) a -> MaybeT m a

MonadWidget (WidgetFor site)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (WidgetFor site)) a -> WidgetFor site a

MonadWidget m => MonadWidget (ExceptT e m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (ExceptT e m)) a -> ExceptT e m a

MonadWidget m => MonadWidget (IdentityT m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (IdentityT m)) a -> IdentityT m a

MonadWidget m => MonadWidget (ReaderT r m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (ReaderT r m)) a -> ReaderT r m a

MonadWidget m => MonadWidget (StateT s m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (StateT s m)) a -> StateT s m a

MonadWidget m => MonadWidget (StateT s m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (StateT s m)) a -> StateT s m a

(Monoid w, MonadWidget m) => MonadWidget (WriterT w m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (WriterT w m)) a -> WriterT w m a

(Monoid w, MonadWidget m) => MonadWidget (WriterT w m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (WriterT w m)) a -> WriterT w m a

MonadWidget m => MonadWidget (ConduitM i o m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (ConduitM i o m)) a -> ConduitM i o m a

(Monoid w, MonadWidget m) => MonadWidget (RWST r w s m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (RWST r w s m)) a -> RWST r w s m a

(Monoid w, MonadWidget m) => MonadWidget (RWST r w s m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (RWST r w s m)) a -> RWST r w s m a

MonadWidget m => MonadWidget (Pipe l i o u m)

Defined in Yesod.Core.Class.Handler

Methods

liftWidget :: WidgetFor (HandlerSite (Pipe l i o u m)) a -> Pipe l i o u m a

Approot

guessApproot :: Approot site

Guess the approot based on request headers. For more information, see Network.Wai.Middleware.Approot

In the case of headers being unavailable, it falls back to ApprootRelative

Since 1.4.16

guessApprootOr :: Approot site -> Approot site

Guess the approot based on request headers, with fall back to the specified AppRoot.

Since 1.4.16

getApprootText :: Approot site -> site -> Request -> Text

Get the textual application root from an Approot value.

Since 1.4.17

Misc

yesodVersion :: String

yesodRender

Arguments

:: Yesod y

=> y

-> ResolvedApproot

-> Route y

-> [(Text, Text)]

url query string

-> Text

runFakeHandler :: (Yesod site, MonadIO m) => SessionMap -> (site -> Logger) -> site -> HandlerT site IO a -> m (Either ErrorResponse a)

Deprecated: import runFakeHandler from Yesod.Core.Unsafe

LiteApp

newtype LiteApp

Constructors

LiteApp

Fields

• unLiteApp :: Method -> [Text] -> Maybe (LiteHandler TypedContent)

Instances

Monoid LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

mempty :: LiteApp

mappend :: LiteApp -> LiteApp -> LiteApp

mconcat :: [LiteApp] -> LiteApp

Semigroup LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

(<>) :: LiteApp -> LiteApp -> LiteApp

sconcat :: NonEmpty LiteApp -> LiteApp

stimes :: Integral b => b -> LiteApp -> LiteApp

YesodDispatch LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

yesodDispatch :: YesodRunnerEnv LiteApp -> Application

Yesod LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

approot :: Approot LiteApp

catchHandlerExceptions :: MonadUnliftIO m => LiteApp -> m a -> (SomeException -> m a) -> m a

errorHandler :: ErrorResponse -> HandlerFor LiteApp TypedContent

defaultLayout :: WidgetFor LiteApp () -> HandlerFor LiteApp Html

urlParamRenderOverride :: LiteApp -> Route LiteApp -> [(Text, Text)] -> Maybe Builder

isAuthorized :: Route LiteApp -> Bool -> HandlerFor LiteApp AuthResult

isWriteRequest :: Route LiteApp -> HandlerFor LiteApp Bool

authRoute :: LiteApp -> Maybe (Route LiteApp)

cleanPath :: LiteApp -> [Text] -> Either [Text] [Text]

joinPath :: LiteApp -> Text -> [Text] -> [(Text, Text)] -> Builder

addStaticContent :: Text -> Text -> ByteString -> HandlerFor LiteApp (Maybe (Either Text (Route LiteApp, [(Text, Text)])))

maximumContentLength :: LiteApp -> Maybe (Route LiteApp) -> Maybe Word64

maximumContentLengthIO :: LiteApp -> Maybe (Route LiteApp) -> IO (Maybe Word64)

makeLogger :: LiteApp -> IO Logger

messageLoggerSource :: LiteApp -> Logger -> Loc -> LogSource -> LogLevel -> LogStr -> IO ()

jsLoader :: LiteApp -> ScriptLoadPosition LiteApp

jsAttributes :: LiteApp -> [(Text, Text)]

jsAttributesHandler :: HandlerFor LiteApp [(Text, Text)]

makeSessionBackend :: LiteApp -> IO (Maybe SessionBackend)

fileUpload :: LiteApp -> RequestBodyLength -> FileUpload

shouldLogIO :: LiteApp -> LogSource -> LogLevel -> IO Bool

yesodMiddleware :: ToTypedContent res => HandlerFor LiteApp res -> HandlerFor LiteApp res

yesodWithInternalState :: LiteApp -> Maybe (Route LiteApp) -> (InternalState -> IO a) -> IO a

defaultMessageWidget :: Html -> HtmlUrl (Route LiteApp) -> WidgetFor LiteApp ()

ParseRoute LiteApp

Defined in Yesod.Core.Internal.LiteApp

Methods

parseRoute :: ([Text], [(Text, Text)]) -> Maybe (Route LiteApp)

RenderRoute LiteApp

Defined in Yesod.Core.Internal.LiteApp

Associated Types

data Route LiteApp

Methods

renderRoute :: Route LiteApp -> ([Text], [(Text, Text)])

Read (Route LiteApp)

Defined in Yesod.Core.Internal.LiteApp

Methods

readsPrec :: Int -> ReadS (Route LiteApp)

readList :: ReadS [Route LiteApp]

readPrec :: ReadPrec (Route LiteApp)

readListPrec :: ReadPrec [Route LiteApp]

Show (Route LiteApp)

Defined in Yesod.Core.Internal.LiteApp

Methods

showsPrec :: Int -> Route LiteApp -> ShowS

show :: Route LiteApp -> String

showList :: [Route LiteApp] -> ShowS

Eq (Route LiteApp)

Defined in Yesod.Core.Internal.LiteApp

Methods

(==) :: Route LiteApp -> Route LiteApp -> Bool

(/=) :: Route LiteApp -> Route LiteApp -> Bool

Ord (Route LiteApp)

Defined in Yesod.Core.Internal.LiteApp

Methods

compare :: Route LiteApp -> Route LiteApp -> Ordering

(<) :: Route LiteApp -> Route LiteApp -> Bool

(<=) :: Route LiteApp -> Route LiteApp -> Bool

(>) :: Route LiteApp -> Route LiteApp -> Bool

(>=) :: Route LiteApp -> Route LiteApp -> Bool

max :: Route LiteApp -> Route LiteApp -> Route LiteApp

min :: Route LiteApp -> Route LiteApp -> Route LiteApp

data Route LiteApp

Defined in Yesod.Core.Internal.LiteApp

data Route LiteApp = LiteAppRoute [Text]

type LiteHandler = HandlerFor LiteApp

type LiteWidget = WidgetFor LiteApp

liteApp :: Writer LiteApp () -> LiteApp

dispatchTo :: ToTypedContent a => LiteHandler a -> Writer LiteApp ()

onMethod :: Method -> Writer LiteApp () -> Writer LiteApp ()

onStatic :: Text -> Writer LiteApp () -> Writer LiteApp ()

withDynamic :: PathPiece p => (p -> Writer LiteApp ()) -> Writer LiteApp ()

withDynamicMulti :: PathMultiPiece ps => (ps -> Writer LiteApp ()) -> Writer LiteApp ()

Low-level

yesodRunner :: forall res site. (ToTypedContent res, Yesod site) => HandlerFor site res -> YesodRunnerEnv site -> Maybe (Route site) -> Application

Re-exports

module Yesod.Core.Content

module Yesod.Core.Dispatch

module Yesod.Core.Handler

module Yesod.Core.Widget

module Yesod.Core.Json

module Text.Shakespeare.I18N

formatW3 :: UTCTime -> Text

Format a UTCTime in W3 format.

formatRFC1123 :: UTCTime -> Text

Format as per RFC 1123.

formatRFC822 :: UTCTime -> Text

Format as per RFC 822.

preEscapedToMarkup :: ToMarkup a => a -> Markup

Convert a value to Markup without escaping

toHtml :: ToMarkup a => a -> Html

type Html = Markup

class MonadTrans (t :: (Type -> Type) -> Type -> Type) where

The class of monad transformers. Instances should satisfy the following laws, which state that lift is a monad transformation:

• lift . return = return

• lift (m >>= f) = lift m >>= (lift . f)

Methods

lift :: Monad m => m a -> t m a

Lift a computation from the argument monad to the constructed monad.

Instances

MonadTrans CatchT

Defined in Control.Monad.Catch.Pure

Methods

lift :: Monad m => m a -> CatchT m a

MonadTrans LoggingT

Defined in Control.Monad.Logger

Methods

lift :: Monad m => m a -> LoggingT m a

MonadTrans NoLoggingT

Defined in Control.Monad.Logger

Methods

lift :: Monad m => m a -> NoLoggingT m a

MonadTrans WriterLoggingT

Defined in Control.Monad.Logger

Methods

lift :: Monad m => m a -> WriterLoggingT m a

MonadTrans ResourceT

Defined in Control.Monad.Trans.Resource.Internal

Methods

lift :: Monad m => m a -> ResourceT m a

MonadTrans ListT

Defined in Control.Monad.Trans.List

Methods

lift :: Monad m => m a -> ListT m a

MonadTrans MaybeT

Defined in Control.Monad.Trans.Maybe

Methods

lift :: Monad m => m a -> MaybeT m a

Monoid w => MonadTrans (AccumT w)

Defined in Control.Monad.Trans.Accum

Methods

lift :: Monad m => m a -> AccumT w m a

MonadTrans (ErrorT e)

Defined in Control.Monad.Trans.Error

Methods

lift :: Monad m => m a -> ErrorT e m a

MonadTrans (ExceptT e)

Defined in Control.Monad.Trans.Except

Methods

lift :: Monad m => m a -> ExceptT e m a

MonadTrans (IdentityT :: (Type -> Type) -> Type -> Type)

Defined in Control.Monad.Trans.Identity

Methods

lift :: Monad m => m a -> IdentityT m a

MonadTrans (ReaderT r)

Defined in Control.Monad.Trans.Reader

Methods

lift :: Monad m => m a -> ReaderT r m a

MonadTrans (SelectT r)

Defined in Control.Monad.Trans.Select

Methods

lift :: Monad m => m a -> SelectT r m a

MonadTrans (StateT s)

Defined in Control.Monad.Trans.State.Lazy

Methods

lift :: Monad m => m a -> StateT s m a

MonadTrans (StateT s)

Defined in Control.Monad.Trans.State.Strict

Methods

lift :: Monad m => m a -> StateT s m a

MonadTrans (WriterT w)

Defined in Control.Monad.Trans.Writer.CPS

Methods

lift :: Monad m => m a -> WriterT w m a

Monoid w => MonadTrans (WriterT w)

Defined in Control.Monad.Trans.Writer.Lazy

Methods

lift :: Monad m => m a -> WriterT w m a

Monoid w => MonadTrans (WriterT w)

Defined in Control.Monad.Trans.Writer.Strict

Methods

lift :: Monad m => m a -> WriterT w m a

MonadTrans (ConduitT i o)

Defined in Data.Conduit.Internal.Conduit

Methods

lift :: Monad m => m a -> ConduitT i o m a

MonadTrans (ParsecT s u)

Defined in Text.Parsec.Prim

Methods

lift :: Monad m => m a -> ParsecT s u m a

MonadTrans (ContT r)

Defined in Control.Monad.Trans.Cont

Methods

lift :: Monad m => m a -> ContT r m a

MonadTrans (RWST r w s)

Defined in Control.Monad.Trans.RWS.CPS

Methods

lift :: Monad m => m a -> RWST r w s m a

Monoid w => MonadTrans (RWST r w s)

Defined in Control.Monad.Trans.RWS.Lazy

Methods

lift :: Monad m => m a -> RWST r w s m a

Monoid w => MonadTrans (RWST r w s)

Defined in Control.Monad.Trans.RWS.Strict

Methods

lift :: Monad m => m a -> RWST r w s m a

MonadTrans (Pipe l i o u)

Defined in Data.Conduit.Internal.Pipe

Methods

lift :: Monad m => m a -> Pipe l i o u m a

class Monad m => MonadIO (m :: Type -> Type) where

Monads in which IO computations may be embedded. Any monad built by applying a sequence of monad transformers to the IO monad will be an instance of this class.

Instances should satisfy the following laws, which state that liftIO is a transformer of monads:

• liftIO . return = return

• liftIO (m >>= f) = liftIO m >>= (liftIO . f)

Methods

liftIO :: IO a -> m a

Lift a computation from the IO monad. This allows us to run IO computations in any monadic stack, so long as it supports these kinds of operations (i.e. IO is the base monad for the stack).

Example

import Control.Monad.Trans.State -- from the "transformers" library

printState :: Show s => StateT s IO ()
printState = do
  state <- get
  liftIO $ print state

Had we omitted liftIO, we would have ended up with this error:

• Couldn't match type ‘IO’ with ‘StateT s IO’
 Expected type: StateT s IO ()
   Actual type: IO ()

The important part here is the mismatch between StateT s IO () and IO ().

Luckily, we know of a function that takes an IO a and returns an (m a): liftIO, enabling us to run the program and see the expected results:

> evalStateT printState "hello"
"hello"

> evalStateT printState 3
3

Instances

MonadIO IO

Since: base-4.9.0.0

Defined in Control.Monad.IO.Class

Methods

liftIO :: IO a -> IO a

MonadIO Acquire

Defined in Data.Acquire.Internal

Methods

liftIO :: IO a -> Acquire a

MonadIO Q

Defined in Language.Haskell.TH.Syntax

Methods

liftIO :: IO a -> Q a

MonadIO m => MonadIO (CatchT m)

Defined in Control.Monad.Catch.Pure

Methods

liftIO :: IO a -> CatchT m a

MonadIO m => MonadIO (LoggingT m)

Defined in Control.Monad.Logger

Methods

liftIO :: IO a -> LoggingT m a

MonadIO m => MonadIO (NoLoggingT m)

Defined in Control.Monad.Logger

Methods

liftIO :: IO a -> NoLoggingT m a

MonadIO m => MonadIO (WriterLoggingT m)

Defined in Control.Monad.Logger

Methods

liftIO :: IO a -> WriterLoggingT m a

MonadIO m => MonadIO (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftIO :: IO a -> ResourceT m a

MonadIO m => MonadIO (ListT m)

Defined in Control.Monad.Trans.List

Methods

liftIO :: IO a -> ListT m a

MonadIO m => MonadIO (MaybeT m)

Defined in Control.Monad.Trans.Maybe

Methods

liftIO :: IO a -> MaybeT m a

MonadIO (HandlerFor site)

Defined in Yesod.Core.Types

Methods

liftIO :: IO a -> HandlerFor site a

MonadIO (WidgetFor site)

Defined in Yesod.Core.Types

Methods

liftIO :: IO a -> WidgetFor site a

(Monoid w, Functor m, MonadIO m) => MonadIO (AccumT w m)

Defined in Control.Monad.Trans.Accum

Methods

liftIO :: IO a -> AccumT w m a

(Error e, MonadIO m) => MonadIO (ErrorT e m)

Defined in Control.Monad.Trans.Error

Methods

liftIO :: IO a -> ErrorT e m a

MonadIO m => MonadIO (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

liftIO :: IO a -> ExceptT e m a

MonadIO m => MonadIO (IdentityT m)

Defined in Control.Monad.Trans.Identity

Methods

liftIO :: IO a -> IdentityT m a

MonadIO m => MonadIO (ReaderT r m)

Defined in Control.Monad.Trans.Reader

Methods

liftIO :: IO a -> ReaderT r m a

MonadIO m => MonadIO (SelectT r m)

Defined in Control.Monad.Trans.Select

Methods

liftIO :: IO a -> SelectT r m a

MonadIO m => MonadIO (StateT s m)

Defined in Control.Monad.Trans.State.Lazy

Methods

liftIO :: IO a -> StateT s m a

MonadIO m => MonadIO (StateT s m)

Defined in Control.Monad.Trans.State.Strict

Methods

liftIO :: IO a -> StateT s m a

MonadIO m => MonadIO (WriterT w m)

Defined in Control.Monad.Trans.Writer.CPS

Methods

liftIO :: IO a -> WriterT w m a

(Monoid w, MonadIO m) => MonadIO (WriterT w m)

Defined in Control.Monad.Trans.Writer.Lazy

Methods

liftIO :: IO a -> WriterT w m a

(Monoid w, MonadIO m) => MonadIO (WriterT w m)

Defined in Control.Monad.Trans.Writer.Strict

Methods

liftIO :: IO a -> WriterT w m a

MonadIO (SubHandlerFor child master)

Defined in Yesod.Core.Types

Methods

liftIO :: IO a -> SubHandlerFor child master a

MonadIO m => MonadIO (ConduitT i o m)

Defined in Data.Conduit.Internal.Conduit

Methods

liftIO :: IO a -> ConduitT i o m a

MonadIO m => MonadIO (ParsecT s u m)

Defined in Text.Parsec.Prim

Methods

liftIO :: IO a -> ParsecT s u m a

MonadIO m => MonadIO (ContT r m)

Defined in Control.Monad.Trans.Cont

Methods

liftIO :: IO a -> ContT r m a

MonadIO m => MonadIO (RWST r w s m)

Defined in Control.Monad.Trans.RWS.CPS

Methods

liftIO :: IO a -> RWST r w s m a

(Monoid w, MonadIO m) => MonadIO (RWST r w s m)

Defined in Control.Monad.Trans.RWS.Lazy

Methods

liftIO :: IO a -> RWST r w s m a

(Monoid w, MonadIO m) => MonadIO (RWST r w s m)

Defined in Control.Monad.Trans.RWS.Strict

Methods

liftIO :: IO a -> RWST r w s m a

MonadIO m => MonadIO (Pipe l i o u m)

Defined in Data.Conduit.Internal.Pipe

Methods

liftIO :: IO a -> Pipe l i o u m a

class MonadIO m => MonadUnliftIO (m :: Type -> Type) where

Monads which allow their actions to be run in IO.

While MonadIO allows an IO action to be lifted into another monad, this class captures the opposite concept: allowing you to capture the monadic context. Note that, in order to meet the laws given below, the intuition is that a monad must have no monadic state, but may have monadic context. This essentially limits MonadUnliftIO to ReaderT and IdentityT transformers on top of IO.

Laws. For any function run provided by withRunInIO, it must meet the monad transformer laws as reformulated for MonadUnliftIO:

• run . return = return

• run (m >>= f) = run m >>= run . f

Instances of MonadUnliftIO must also satisfy the following laws:

Identity law

withRunInIO (\run -> run m) = m

Inverse law

withRunInIO (\_ -> m) = liftIO m

As an example of an invalid instance, a naive implementation of MonadUnliftIO (StateT s m) might be

withRunInIO inner =
  StateT $ \s ->
    withRunInIO $ \run ->
      inner (run . flip evalStateT s)

This breaks the identity law because the inner run m would throw away any state changes in m.

Since: unliftio-core-0.1.0.0

Methods

withRunInIO :: ((forall a. m a -> IO a) -> IO b) -> m b

Convenience function for capturing the monadic context and running an IO action with a runner function. The runner function is used to run a monadic action m in IO.

Since: unliftio-core-0.1.0.0

Instances

MonadUnliftIO IO

Defined in Control.Monad.IO.Unlift

Methods

withRunInIO :: ((forall a. IO a -> IO a) -> IO b) -> IO b

MonadUnliftIO m => MonadUnliftIO (LoggingT m)

Since: monad-logger-0.3.26

Defined in Control.Monad.Logger

Methods

withRunInIO :: ((forall a. LoggingT m a -> IO a) -> IO b) -> LoggingT m b

MonadUnliftIO m => MonadUnliftIO (NoLoggingT m)

Since: monad-logger-0.3.26

Defined in Control.Monad.Logger

Methods

withRunInIO :: ((forall a. NoLoggingT m a -> IO a) -> IO b) -> NoLoggingT m b

MonadUnliftIO m => MonadUnliftIO (ResourceT m)

Since: resourcet-1.1.10

Defined in Control.Monad.Trans.Resource.Internal

Methods

withRunInIO :: ((forall a. ResourceT m a -> IO a) -> IO b) -> ResourceT m b

MonadUnliftIO (HandlerFor site)

Since: 1.4.38

Defined in Yesod.Core.Types

Methods

withRunInIO :: ((forall a. HandlerFor site a -> IO a) -> IO b) -> HandlerFor site b

MonadUnliftIO (WidgetFor site)

Since: 1.4.38

Defined in Yesod.Core.Types

Methods

withRunInIO :: ((forall a. WidgetFor site a -> IO a) -> IO b) -> WidgetFor site b

MonadUnliftIO m => MonadUnliftIO (IdentityT m)

Defined in Control.Monad.IO.Unlift

Methods

withRunInIO :: ((forall a. IdentityT m a -> IO a) -> IO b) -> IdentityT m b

MonadUnliftIO m => MonadUnliftIO (ReaderT r m)

Defined in Control.Monad.IO.Unlift

Methods

withRunInIO :: ((forall a. ReaderT r m a -> IO a) -> IO b) -> ReaderT r m b

MonadUnliftIO (SubHandlerFor child master)

Since: 1.4.38

Defined in Yesod.Core.Types

Methods

withRunInIO :: ((forall a. SubHandlerFor child master a -> IO a) -> IO b) -> SubHandlerFor child master b

class MonadIO m => MonadResource (m :: Type -> Type) where

A Monad which allows for safe resource allocation. In theory, any monad transformer stack which includes a ResourceT can be an instance of MonadResource.

Note: runResourceT has a requirement for a MonadUnliftIO m monad, which allows control operations to be lifted. A MonadResource does not have this requirement. This means that transformers such as ContT can be an instance of MonadResource. However, the ContT wrapper will need to be unwrapped before calling runResourceT.

Since 0.3.0

Methods

liftResourceT :: ResourceT IO a -> m a

Lift a ResourceT IO action into the current Monad.

Since 0.4.0

Instances

MonadResource m => MonadResource (LoggingT m)

Defined in Control.Monad.Logger

Methods

liftResourceT :: ResourceT IO a -> LoggingT m a

MonadResource m => MonadResource (NoLoggingT m)

Defined in Control.Monad.Logger

Methods

liftResourceT :: ResourceT IO a -> NoLoggingT m a

MonadIO m => MonadResource (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ResourceT m a

MonadResource m => MonadResource (ListT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ListT m a

MonadResource m => MonadResource (MaybeT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> MaybeT m a

MonadResource (HandlerFor site)

Defined in Yesod.Core.Types

Methods

liftResourceT :: ResourceT IO a -> HandlerFor site a

MonadResource (WidgetFor site)

Defined in Yesod.Core.Types

Methods

liftResourceT :: ResourceT IO a -> WidgetFor site a

MonadResource m => MonadResource (ExceptT e m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ExceptT e m a

MonadResource m => MonadResource (IdentityT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> IdentityT m a

MonadResource m => MonadResource (ReaderT r m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ReaderT r m a

MonadResource m => MonadResource (StateT s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> StateT s m a

MonadResource m => MonadResource (StateT s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> StateT s m a

(Monoid w, MonadResource m) => MonadResource (WriterT w m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> WriterT w m a

(Monoid w, MonadResource m) => MonadResource (WriterT w m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> WriterT w m a

MonadResource (SubHandlerFor child master)

Defined in Yesod.Core.Types

Methods

liftResourceT :: ResourceT IO a -> SubHandlerFor child master a

MonadResource m => MonadResource (ConduitT i o m)

Defined in Data.Conduit.Internal.Conduit

Methods

liftResourceT :: ResourceT IO a -> ConduitT i o m a

MonadResource m => MonadResource (ContT r m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ContT r m a

(Monoid w, MonadResource m) => MonadResource (RWST r w s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> RWST r w s m a

(Monoid w, MonadResource m) => MonadResource (RWST r w s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> RWST r w s m a

MonadResource m => MonadResource (Pipe l i o u m)

Defined in Data.Conduit.Internal.Pipe

Methods

liftResourceT :: ResourceT IO a -> Pipe l i o u m a

class Monad m => MonadLogger (m :: Type -> Type)

A Monad which has the ability to log messages in some manner.

Instances

MonadIO m => MonadLogger (LoggingT m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> LoggingT m ()

Monad m => MonadLogger (NoLoggingT m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> NoLoggingT m ()

Monad m => MonadLogger (WriterLoggingT m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> WriterLoggingT m ()

MonadLogger m => MonadLogger (ResourceT m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> ResourceT m ()

MonadLogger m => MonadLogger (ListT m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> ListT m ()

MonadLogger m => MonadLogger (MaybeT m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> MaybeT m ()

MonadLogger (HandlerFor site)

Defined in Yesod.Core.Types

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> HandlerFor site ()

MonadLogger (WidgetFor site)

Defined in Yesod.Core.Types

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> WidgetFor site ()

(MonadLogger m, Error e) => MonadLogger (ErrorT e m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> ErrorT e m ()

MonadLogger m => MonadLogger (ExceptT e m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> ExceptT e m ()

MonadLogger m => MonadLogger (IdentityT m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> IdentityT m ()

MonadLogger m => MonadLogger (ReaderT r m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> ReaderT r m ()

MonadLogger m => MonadLogger (StateT s m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> StateT s m ()

MonadLogger m => MonadLogger (StateT s m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> StateT s m ()

(MonadLogger m, Monoid w) => MonadLogger (WriterT w m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> WriterT w m ()

(MonadLogger m, Monoid w) => MonadLogger (WriterT w m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> WriterT w m ()

MonadLogger (SubHandlerFor child master)

Defined in Yesod.Core.Types

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> SubHandlerFor child master ()

MonadLogger m => MonadLogger (ConduitM i o m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> ConduitM i o m ()

MonadLogger m => MonadLogger (ContT r m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> ContT r m ()

(MonadLogger m, Monoid w) => MonadLogger (RWST r w s m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> RWST r w s m ()

(MonadLogger m, Monoid w) => MonadLogger (RWST r w s m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> RWST r w s m ()

MonadLogger m => MonadLogger (Pipe l i o u m)

Defined in Control.Monad.Logger

Methods

monadLoggerLog :: ToLogStr msg => Loc -> LogSource -> LogLevel -> msg -> Pipe l i o u m ()

Commonly referenced functions/datatypes

type Application = Request -> (Response -> IO ResponseReceived) -> IO ResponseReceived

The WAI application.

Note that, since WAI 3.0, this type is structured in continuation passing style to allow for proper safe resource handling. This was handled in the past via other means (e.g., ResourceT). As a demonstration:

app :: Application
app req respond = bracket_
    (putStrLn "Allocating scarce resource")
    (putStrLn "Cleaning up")
    (respond $ responseLBS status200 [] "Hello World")

Utilities

showIntegral :: Integral a => a -> String

readIntegral :: Num a => String -> Maybe a

Shakespeare

Hamlet

hamlet :: QuasiQuoter

Hamlet quasi-quoter. May only be used to generate expressions.

Generated expression have type HtmlUrl url, for some url.

data MyRoute = Home

render :: Render MyRoute
render Home _ = "/home"

>>> putStrLn (renderHtml ([hamlet|<a href=@{Home}>Home|] render))
<a href="/home">Home</a>

shamlet :: QuasiQuoter

"Simple Hamlet" quasi-quoter. May only be used to generate expressions.

Generated expressions have type Html.

>>> putStrLn (renderHtml [shamlet|<div>Hello, world!|])
<div>Hello, world!</div>

xhamlet :: QuasiQuoter

Like hamlet, but produces XHTML.

type HtmlUrl url = Render url -> Html

A function generating an Html given a URL-rendering function.

Julius

julius :: QuasiQuoter

type JavascriptUrl url = (url -> [(Text, Text)] -> Text) -> Javascript

Return type of template-reading functions.

renderJavascriptUrl :: (url -> [(Text, Text)] -> Text) -> JavascriptUrl url -> Text

render with route interpolation. If using this module standalone, apart from type-safe routes, a dummy renderer can be used:

renderJavascriptUrl (\_ _ -> undefined) javascriptUrl

When using Yesod, a renderer is generated for you, which can be accessed within the GHandler monad: getUrlRenderParams.

Cassius/Lucius

cassius :: QuasiQuoter

lucius :: QuasiQuoter

>>> renderCss ([lucius|foo{bar:baz}|] undefined)
"foo{bar:baz}"

type CssUrl url = (url -> [(Text, Text)] -> Text) -> Css

renderCssUrl :: (url -> [(Text, Text)] -> Text) -> CssUrl url -> Text