dyre-0.9.2: Dynamic reconfiguration in Haskell

Safe Haskell | None
Language | Haskell2010

Config.Dyre.Relaunch

Description

This is the only other module aside from Config.Dyre which needs to be imported specially. It contains functions for restarting the program (which, usefully, will cause a recompile if the config has been changed), as well as saving and restoring state across said restarts.

The impossibly simple function arguments are a consequence of a little cheating we do using the System.IO.Storage library. Of course, we can't use the stored data unless something else put it there, so this module will probably explode horribly if used outside of a program whose recompilation is managed by Dyre.

The functions for saving and loading state come in two variants: one which uses the `Read` and `Show` typeclasses, and one which uses Data.Binary to serialize it. The `Read` and `Show` versions are much easier to use thanks to automatic deriving, but the binary versions offer more control over saving and loading, as well as probably being a bit faster.

Synopsis

- relaunchMaster :: Maybe [String] -> IO ()
- relaunchWithTextState :: Show a => a -> Maybe [String] -> IO ()
- relaunchWithBinaryState :: Binary a => a -> Maybe [String] -> IO ()
- saveTextState :: Show a => a -> IO ()
- saveBinaryState :: Binary a => a -> IO ()
- restoreTextState :: Read a => a -> IO a
- restoreBinaryState :: Binary a => a -> IO a

# Documentation

relaunchMaster :: Maybe [String] -> IO () Source #

Just relaunch the master binary. We don't have any important state to worry about. (Or, like when `relaunchWith<X>State` calls it, we're managing state on our own). It takes an argument which can optionally specify a new set of arguments. If it is given a value of `Nothing`, the current value of `getArgs` will be used.

relaunchWithTextState :: Show a => a -> Maybe [String] -> IO () Source #

Relaunch the master binary, but first preserve the program state so that we can use the `restoreTextState` functions to get it back again later.

relaunchWithBinaryState :: Binary a => a -> Maybe [String] -> IO () Source #

Serialize the state for later restoration with `restoreBinaryState`, and then relaunch the master binary.

saveTextState :: Show a => a -> IO () Source #

Serialize a state as text, for later loading with the `restoreTextState` function.

saveBinaryState :: Binary a => a -> IO () Source #

Serialize a state as binary data, for later loading with the `restoreBinaryState` function.

restoreTextState :: Read a => a -> IO a Source #

Restore state which has been serialized through the `saveTextState` function. Takes a default which is returned if the state doesn't exist.

restoreBinaryState :: Binary a => a -> IO a Source #

Restore state which has been serialized through the `saveBinaryState` function. Takes a default which is returned if the state doesn't exist.