[Haskell] ANNOUNCE: ghc-visvxvzvzvv

ian.knopke at gmail.com ian.knopke at gmail.com
Sat Sep 1 16:32:01 CEST 2012

Sent from my BlackBerry® wireless device

-----Original Message-----
From: Ivan Lazar Miljenovic <ivan.miljenovic at gmail.com>
Sender: haskell-bounces at haskell.org
Date: Sat, 1 Sep 2012 20:52:22 
To: Dennis Felsing<dennis at felsin9.de>
Cc: <haskell at haskell.org>
Subject: Re: [Haskell] ANNOUNCE: ghc-vis

On 1 September 2012 17:27, Dennis Felsing <dennis at felsin9.de> wrote:
> Hello,
> I'm pleased to announce the relase of ghc-vis. This package provides a
> way to visualize live data structures in GHCi, similar to GHCi's :print
> and vacuum-cairo. Evaluation is not forced and you can interact with the
> visualized data structures. This allows seeing Haskell's lazy evaluation
> and sharing in action. Hopefully it will be useful for teaching Haskell
> and understanding and debugging data structures.
> Currently there's a linear view and a graph view using GraphViz. If you
> want to see some examples of how it looks head to
> http://felsin9.de/nnis/ghc-vis/
> or just give it a try like this:
> $ cabal install ghc-vis
> $ echo ":script $HOME/.cabal/share/ghc-vis-0.2.1/ghci" >> ~/.ghci
> $ ghci
> GHCi, version 7.4.2: http://www.haskell.org/ghc/  :? for help
> λ> :vis
> λ> let a = [1..3]
> λ> :view a
> λ> let b = cycle a
> λ> :view b
> λ> :view "foo" ++ "bar"
> λ> :eval t1
> λ> :switch
> On Hackage: http://hackage.haskell.org/package/ghc-vis
> I'm happy to hear about bugs, feature requests and other thoughts.
> Dennis

In terms of your usage of graphviz, I have a couple of suggestions (as
it's maintainer ;-) on how you can improve your code:

* As of graphviz-2999.14.1.0, I've introduced isGraphvizInstalled and
quitWithoutGraphviz to try and prevent closed pipe errors when you try
to call dot when it isn't installed

* I suggest you use either hGetDot or hGetStrict from
Data.GraphViz.Commands.IO rather than hGetContents in your
GHC.Vis.Graph.dg function (maybe

Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com

Haskell mailing list
Haskell at haskell.org

More information about the Haskell mailing list