Graphics.Rendering.OpenGL.GL.Exception

This is a purely internal module to compensate for differences between Haskell implementations.

Documentation

bracket

Arguments

:: IO a

computation to run first ("acquire resource")

-> (a -> IO b)

computation to run last ("release resource")

-> (a -> IO c)

computation to run in-between

-> IO c

When you want to acquire a resource, do some work with it, and then release the resource, it is a good idea to use bracket, because bracket will install the necessary exception handler to release the resource in the event that an exception is raised during the computation. If an exception is raised, then bracket will re-raise the exception (after performing the release).

A common example is opening a file:

 bracket
   (openFile "filename" ReadMode)
   (hClose)
   (\fileHandle -> do { ... })

The arguments to bracket are in this order so that we can partially apply it, e.g.:

 withFile name mode = bracket (openFile name mode) hClose

bracket_ :: IO a -> IO b -> IO c -> IO c

A variant of bracket where the return value from the first computation is not required.

unsafeBracket_ :: IO a -> IO b -> IO c -> IO c

finallyRet :: IO a -> IO b -> IO (a, b)