RE: finding the dependecies of cabal packages

[ oops, hit send by mistake ] On 01 August 2005 11:31, Krasimir Angelov wrote:

Visual Haskell works quite well with hooks.

Hmm, I'm not sure it does. The hooks are only run when building the project, not when interactively editing the source code. We can't discover what hooks are being used, because they are embedded in the Setup.lhs script. The preXXX hooks are a one-way mechanism for obtaining the PackageDescription: there's no way to re-inject a modified PackageDescription. The postXXX hooks, on the other hand, are fine. As long as you stick to postXXX hooks, then VH works fine, because the PackageDescrption is static and in a known place. This isn't an argument against hooks, just an observation that (a) there are uses of hooks that work fine with an IDE, (b) there are uses of hooks that don't, and (c) the IDE can't tell whether a package is even using hooks, let alone whether it is using safe hooks or not. We should at least do something about (c). Sorry for not bringing this up when hooks were being discussed... Cheers, Simon

We are already using hooks in order to build Visual Haskell itself. In Visual C++ projects you can specify a sequence of shell commands which can be executed at specified point in the build process. In Visual Haskell you can use Cabal hooks to perform the same actions but the hooks approach is more flexible. The only limitation of Visual Haskell is that it can work only with the simple build architecture. It can be extended with the makefile based system but the drawback will be that we will lose the project editing features, interactive type checking and all other advanced features. The situation is the same with the Makefile based Visual C++ projects. Visual C++ provides only basic support for Makefiles.

Cheers, Krasimir

On 8/1/05, Simon Marlow wrote:

...

On 29 July 2005 21:18, Duncan Coutts wrote:

...

However an IDE wants even more. It wants to be able to rebuild individual files quickly (so dependency tracking is required and linear build scripts are out). It will want to provide a GUI interface for changing build system parameters (which means that the build system has to be declarative, not scripted). And no doubt there are other things too.

The point is that fulfilling these requirements might be possible for some imagined future version of the "simple" build system, however if the Cabal interface is extended to stipulate these same features then it would exclude most other build system implementations.

My feeling is that the requirements for incremental building should be part of the simple build system.

It's not quite true now, because we allow arbitrary hooks into the simple build system. So tools like Visual Haskell only work properly if you don't use hooks. This is one reason why being more explicit about whether a package uses hooks or not would be useful.

Cheers, Simon _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries