Hi Neil, It sounds a lot to me like:

* Create a visual meta-language * Program with diagrams * Translate to Haskell

Yes, that is true and I guess this is a standard procedure, isn't it? The translation process is not at all different from your "Translate to C++". The difference is the Visual Language. It is hard to understand a program just by reading the code. An easy to understand visual notation can ease the understandability of your programs. Nowadays there are so many tools out there, that it is very easy to implement such a visual language. A decade ago there already was research in this direction, however, it was pretty "make a good tool"-oriented. Today we could tackle the visual notation with all forces and get the tool support for free (nearly). For example, the notion of a package diagram is for Haskell as useful as for OOP languages, because it can help you to understand the overall structure of a program. On a deeper level you could plug together a visual language for type class hierarchies (similar to but of course not equivalent to class diagrams), a "type-construction-language" and what else comes to your mind and get a Haskell CASE tool. The problem of modeling+editing is nearly solved in the OOP world (see FUJABA for instance or EMFs JMerge). openArchitectureWare lets you define protected regions for this purpose - a very general approach that is not so good for readability. You say Haskell is good for implementing DSLs, yeah, than it will be no problem to define a DSL for itself :-) Ciao, Steffen If thats the case, how is "Translate to Haskell" different from

"Translate to C++"? It only makes a difference if you go in and edit the result, but then you've lost your model?

The other thing is that defining a domain specific language is well understood in Haskell, and generally looks quite nice. The advantage is that it can integrate with the rest of Haskell easily - if you take away the Haskell and move into the realm of models I don't see how you can keep this selling point.

(Personal note: I detest modelling languages with a passion, and I love Haskell with a passion - I'm curious whether I love or hate the combination)

Thanks

Neil

...

I have done some experiments relating to our discussion. The approach to generate Haskell code from UML class diagrams is not very promising. However one may define a visual notation of Haskell (this is no new idea of course), provide better tool support (in particular editor+code generator) and

...

the Haskellers away from vim, emacs or even from the Visual Studio Plugin "Visual Haskell", that is more a Haskell IDE Integration than a visual programming environment (great work either way!).

I have described a possible toolchain towards a real Visual Haskell at my blog:

http://www.steffen-mazanek.de/blog/2007/05/visual-language-howto.html

Best regards, Steffen

2007/4/14, Brian Smith :

...

On 4/14/07, Steffen Mazanek wrote:

...

Brian, but don't you think that you have to write a lot of boilerplate code in Haskell?

I have never felt I was writing a lot of boilerplate. There are a lot of abstraction mechanisms in Haskell to avoid boilerplate.

...

Second, if Haskell should be more successful in the real world there has to be a way of demonstrating basic ideas of a big program to "customers". How would you do this? Everybody knows UML class diagrams, for example. In contrast, nobody knows about termgraphs or lambda *g*.

I've never had to show a UML or ER diagram to any business

On 5/9/07, Steffen Mazanek wrote: pull people--usually

...

they want a slideshow that is far simpler and a little prettier. The fact that "nobody knows about termgraphs or lambda" in your group means that you probably shouldn't be considering Haskell (for the same reason my bosses always asked me to document everything--"in case you get hit by a bus").

...

...

Thank you very much for contributing to the discussion. Please assume, that you have to generate the code from a model. Further assume, that you have no choice and are not allowed to discuss the sense of this approach :-) How should the code look like?

I am not sure if you are trying to solve a real problem or not. If you

are solving a real problem, where you already happen to have an EMF model which you are required to generate code from, then I recommend to just do everything in Java using the existing tools built for EMF.

...

If you decide to still keep working in Haskell, and it works out well,

please share your solution because I think many people here will be very interested. wxHaskell, OOHaskell, and O'Haskell are all starting points for this type of project.

...

- Brian

-- Dipl.-Inform. Steffen Mazanek Institut für Softwaretechnologie Fakultät Informatik

Universität der Bundeswehr München 85577 Neubiberg

Tel: +49 (0)89 6004-2505 Fax: +49 (0)89 6004-4447

E-Mail: steffen.mazanek@unibw.de _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

-- Dipl.-Inform. Steffen Mazanek Institut für Softwaretechnologie Fakultät Informatik Universität der Bundeswehr München 85577 Neubiberg Tel: +49 (0)89 6004-2505 Fax: +49 (0)89 6004-4447 E-Mail: steffen.mazanek@unibw.de