Copyright	(C) 2016-2018 David M. Johnson
License	BSD3-style (see the file LICENSE)
Maintainer	David M. Johnson <djohnson.m@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	None
Language	Haskell2010

Miso.Effect

Description

This module defines Effect and Sub types, which are used to define update function and subs field of the App.

Synopsis

module Miso.Effect.Storage
module Miso.Effect.DOM
data Effect action model = Effect model [Sub action]
type Sub action = Sink action -> JSM ()
type Sink action = action -> IO ()
mapSub :: (actionA -> actionB) -> Sub actionA -> Sub actionB
noEff :: model -> Effect action model
(<#) :: model -> JSM action -> Effect action model
(#>) :: JSM action -> model -> Effect action model
batchEff :: model -> [JSM action] -> Effect action model
effectSub :: model -> Sub action -> Effect action model

Documentation

module Miso.Effect.Storage

module Miso.Effect.DOM

data Effect action model Source #

An effect represents the results of an update action.

It consists of the updated model and a list of subscriptions. Each Sub is run in a new thread so there is no risk of accidentally blocking the application.

Constructors

Effect model [Sub action]

Instances

Bifunctor Effect Source #
Instance details Defined in Miso.Effect Methods bimap :: (a -> b) -> (c -> d) -> Effect a c -> Effect b d Source # first :: (a -> b) -> Effect a c -> Effect b c Source # second :: (b -> c) -> Effect a b -> Effect a c Source #
Monad (Effect action) Source #
Instance details Defined in Miso.Effect Methods (>>=) :: Effect action a -> (a -> Effect action b) -> Effect action b Source # (>>) :: Effect action a -> Effect action b -> Effect action b Source # return :: a -> Effect action a Source # fail :: String -> Effect action a Source #
Functor (Effect action) Source #
Instance details Defined in Miso.Effect Methods fmap :: (a -> b) -> Effect action a -> Effect action b Source # (<$) :: a -> Effect action b -> Effect action a Source #
Applicative (Effect action) Source #
Instance details Defined in Miso.Effect Methods pure :: a -> Effect action a Source # (<>) :: Effect action (a -> b) -> Effect action a -> Effect action b Source # liftA2 :: (a -> b -> c) -> Effect action a -> Effect action b -> Effect action c Source # (>) :: Effect action a -> Effect action b -> Effect action b Source # (<*) :: Effect action a -> Effect action b -> Effect action a Source #

type Sub action = Sink action -> JSM () Source #

Type synonym for constructing event subscriptions.

The Sink callback is used to dispatch actions which are then fed back to the update function.

type Sink action = action -> IO () Source #

Function to asynchronously dispatch actions to the update function.

mapSub :: (actionA -> actionB) -> Sub actionA -> Sub actionB Source #

Turn a subscription that consumes actions of type a into a subscription that consumes actions of type b using the supplied function of type a -> b.

noEff :: model -> Effect action model Source #

Smart constructor for an Effect with no actions.

(<#) :: model -> JSM action -> Effect action model Source #

Smart constructor for an Effect with exactly one action.

(#>) :: JSM action -> model -> Effect action model Source #

Effect smart constructor, flipped

batchEff :: model -> [JSM action] -> Effect action model Source #

Smart constructor for an Effect with multiple actions.

effectSub :: model -> Sub action -> Effect action model Source #

Like <# but schedules a subscription which is an IO computation which has access to a Sink which can be used to asynchronously dispatch actions to the update function.

A use-case is scheduling an IO computation which creates a 3rd-party JS widget which has an associated callback. The callback can then call the sink to turn events into actions. To do this without accessing a sink requires going via a Subscription which introduces a leaky-abstraction.