Reminds me of To Dissect a Mockingbird [http://dkeenan.com/Lambda/]. On Tue, Mar 23, 2010 at 7:12 AM, Ivan Miljenovic wrote:

On 23 March 2010 10:02, Dupont Corentin wrote:

...

I’m relatively new to Haskell.

Welcome!

...

I’m wondering if it exist a tool to graphically represent Haskell code.

Look at the little graphics at: http://www.haskell.org/arrows/index.html (and following pages) from Ross Paterson.

If found these very useful to understand the Arrow monad.

Why not automatise this in a tool? Such a tool could draw a graphic from the code of a program.

1) Because no-one has written such a tool yet (though someone has suggested doing one as a GSoC project). 2) I'm of the opinion that unless you just use it on small snippets, the generated images will be too large and unweildy.

...

This could be done entirely automatically from the types of the functions.

Except not everyone provides type signatures for their functions; whilst it may be possible to use the GHC API to infer these type signatures, my understanding is that it's preferable to use other parsers such as haskell-src-exts as the GHC API is unstable.

[shameless plug] My SourceGraph (http://hackage.haskell.org/package/SourceGraph) tool does function call visualisation as part of its analyses. [/shameless plug]

-- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

On Mon, Mar 22, 2010 at 7:02 PM, Dupont Corentin wrote:

Hello, I’m relatively new to Haskell. I’m wondering if it exist a tool to graphically represent Haskell code. ... Let’s try to do it on a simple example, as an exercise: f = Map (+1)

Your graphic for "f = map (+1)" seems much more complex than the corresponding code. I would agree with Ivan Miljenovic:

I'm of the opinion that unless you just use it on small snippets, the generated images will be too large and unwieldy.

The first question I would ask is /why/ would you like to visualize some Haskell code? If you want to see the high-level structure of a complex program, try SourceGraph. (I have never used it though.) On the other hand, if you are trying to visualize Haskell as part of your efforts to learn the language, then I believe it would be best to draw diagrams by hand, rather than relying on an automated tool. The kinds of things that you'll want to depict are probably going to vary considerably, depending on what you're trying to understand. Consider a few different implementations of the "map" function: -- version 1: recursion map1 :: (a -> b) -> [a] -> [b] map1 f [] = [] map1 f (x:xs) = (f x) : map1 f xs -- version 2: fold map2 :: (a -> b) -> [a] -> [b] map2 f = foldr ((:) . f) [] -- version 3: continuation passing style map3 :: (a -> b) -> [a] -> [b] map3 f xs = map' (\x y -> f x : y) xs where map' k [] = [] map' k (y:ys) = k y (map' k ys) -- version 4: list comprehension map4 :: (a -> b) -> [a] -> [b] map4 f xs = [f x | x <- xs] -- version 5: list monad map5 :: (a -> b) -> [a] -> [b] map5 f xs = xs >>= (return . f) These all do exactly the same thing, but each one uses different techniques. If I'm trying to learn (or teach) Haskell, I would probably need a slightly different visual "language" for each one in order to capture the most relevant concepts in a useful way. How would you visualize them? @Mihai Maruseac: I think a visual debugger would be a wonderful idea. You may want to consider how a visual debugger would work with each of these versions of map. :-) You might also consider several versions of factorial :-) http://www.willamette.edu/~fruehr/haskell/evolution.html -- Ron