Copyright	2011 John Millikin
License	MIT
Maintainer	jmillikin@gmail.com
Portability	GHC only
Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Knob

Description

Create memory‐backed Handles, referencing virtual files. This is mostly useful for testing Handle‐based APIs without having to interact with the filesystem.

import Data.ByteString (pack)
import Data.Knob
import System.IO

main = do
    knob <- newKnob (pack [])
    h <- newFileHandle knob "test.txt" WriteMode
    hPutStrLn h "Hello world!"
    hClose h
    bytes <- Data.Knob.getContents knob
    putStrLn ("Wrote bytes: " ++ show bytes)

Synopsis

data Knob
newKnob :: MonadIO m => ByteString -> m Knob
getContents :: MonadIO m => Knob -> m ByteString
setContents :: MonadIO m => Knob -> ByteString -> m ()
newFileHandle :: MonadIO m => Knob -> String -> IOMode -> m Handle
withFileHandle :: MonadIO m => Knob -> String -> IOMode -> (Handle -> IO a) -> m a

Documentation

data Knob Source #

A knob is a basic virtual file, which contains a byte buffer. A knob can have multiple Handles open to it, each of which behaves like a standard file handle.

Use getContents and setContents to inspect and modify the knob's byte buffer.

newKnob :: MonadIO m => ByteString -> m Knob Source #

getContents :: MonadIO m => Knob -> m ByteString Source #

setContents :: MonadIO m => Knob -> ByteString -> m () Source #

newFileHandle Source #

Arguments

:: MonadIO m
=> Knob
-> String	Filename shown in error messages
-> IOMode
-> m Handle

Create a new Handle pointing to a Knob. This handle behaves like a file-backed handle for most purposes.

withFileHandle Source #

Arguments

:: MonadIO m
=> Knob
-> String	Filename shown in error messages.
-> IOMode
-> (Handle -> IO a)
-> m a

See newFileHandle.