GHC.Vis

Although ghc-vis is meant to be used in GHCi it can also be used as a library in regular Haskell programs which are run or compiled by GHC. You can run those programs using "runghc example.hs" or "ghc -threaded example.hs && ./example". Without the "-threaded"-Flag ghc-vis does not work correctly. This is an example using ghc-vis outside of GHCi:

 import GHC.Vis

 main = do
   putStrLn "Start"
   let a = "teeest"
   let b = [1..3]
   let c = b ++ b
   let d = [1..]
   putStrLn $ show $ d !! 1

   visualization
   view a "a"
   view b "b"
   view c "c"
   view d "d"

   getChar
   switch

   getChar
   putStrLn "End"

Documentation

visualization :: IO ()

This is the main function. It's to be called from GHCi and launches a graphical window in a new thread.

view :: a -> String -> IO ()

Add expressions with a name to the visualization window.

eval :: String -> IO ()

Evaluate an object that is shown in the visualization. (Names start with t)

switch :: IO ()

Switch between the list view and the graph view

update :: IO ()

When an object is updated by accessing it, you have to call this to refresh the visualization window. You can also click on an object to force an update.

clear :: IO ()

Clear the visualization window, removing all expressions from it.

export :: String -> IO ()

Export the current visualization view to an SVG file.