miso

Copyright	(C) 2016-2026 David M. Johnson
License	BSD3-style (see the file LICENSE)
Maintainer	David M. Johnson <code@dmj.io>
Stability	experimental
Portability	non-portable
Safe Haskell	None
Language	Haskell2010

Miso.Storage

Contents

Local
Session

Description

Overview

Miso.Storage wraps the browser's Web Storage API, providing access to both localStorage and sessionStorage through symmetric IO functions.

Both stores map MisoString keys to MisoString values (the Web Storage API only persists strings). Reads return Maybe MisoString — Nothing when the key is absent.

localStorage — persists across browser sessions until explicitly cleared.
sessionStorage — persists only for the lifetime of the current browser tab/session; cleared automatically when the tab is closed.

Quick start

import Miso.Storage
import Miso.String (ms)

-- Persist a preference
saveTheme :: MisoString -> IO ()
saveTheme theme = setLocalStorage "theme" theme

-- Restore it on startup
loadTheme :: IO (Maybe MisoString)
loadTheme = getLocalStorage "theme"

-- Session-scoped token (cleared when tab closes)
saveToken :: MisoString -> IO ()
saveToken tok = setSessionStorage "auth_token" tok

API groups

localStorage: getLocalStorage, setLocalStorage, removeLocalStorage, clearLocalStorage, localStorageLength
sessionStorage: getSessionStorage, setSessionStorage, removeSessionStorage, clearSessionStorage, sessionStorageLength

See also

Miso.Effect — schedule storage reads/writes with io / io_
Miso.Subscription.History — URL-based state that survives page reloads

Synopsis

getLocalStorage :: MisoString -> IO (Maybe MisoString)
setLocalStorage :: MisoString -> MisoString -> IO ()
removeLocalStorage :: MisoString -> IO ()
clearLocalStorage :: IO ()
localStorageLength :: IO Int
getSessionStorage :: MisoString -> IO (Maybe MisoString)
setSessionStorage :: MisoString -> MisoString -> IO ()
removeSessionStorage :: MisoString -> IO ()
clearSessionStorage :: IO ()
sessionStorageLength :: IO Int

Local

getLocalStorage Source #

Arguments

:: MisoString	Storage key to look up
-> IO (Maybe MisoString)

Retrieves a value stored under the given key in local storage.

setLocalStorage Source #

Arguments

:: MisoString	Storage key to set
-> MisoString	Value to store
-> IO ()

Sets the value of a key in local storage.

setLocalStorage key value sets the value of key to value.

removeLocalStorage Source #

Arguments

:: MisoString	Storage key to remove
-> IO ()

Removes an item from local storage.

removeLocalStorage key removes the value of key.

clearLocalStorage :: IO () Source #

Clears local storage.

clearLocalStorage removes all values from local storage.

localStorageLength :: IO Int Source #

Returns the number of items in local storage.

localStorageLength returns the count of items in local storage

Session

getSessionStorage Source #

Arguments

:: MisoString	Storage key to look up
-> IO (Maybe MisoString)

Retrieves a value stored under the given key in session storage.

setSessionStorage Source #

Arguments

:: MisoString	Storage key to set
-> MisoString	Value to store
-> IO ()

Sets the value of a key in session storage.

setSessionStorage key value sets the value of key to value.

removeSessionStorage Source #

Arguments

:: MisoString	Storage key to remove
-> IO ()

Removes an item from session storage.

removeSessionStorage key removes the value of key.

clearSessionStorage :: IO () Source #

Clears session storage.

clearSessionStorage removes all values from session storage.

sessionStorageLength :: IO Int Source #

Returns the number of items in session storage.

sessionStorageLength returns the count of items in session storage