On Sun, 2009-11-08 at 20:47 -0800, Gregory Crosswhite wrote:
Actually, let me clarify my point: I have rarely encountered problems when using Cabal as a package distribution system, but I have run into problems when using it as a build system in a non-trivial manner. For example, when I wanted to build a lot of small utility programs I found that it was re-compiling commonly-shared source files for each program, rather than compiling the source file once and re-using the object file. This was sufficiently annoying that I migrated the build process of my utilities to scons.
You'll be glad to know this is addressed in Cabal-1.8, though not in a fully automatic way. The problem with sharing automatically is knowing when it is safe to do so and when it is not. Each component that shares a source file can use different compiler options, cpp flags, and include dirs (and perhaps other stuff that we cannot easily track). Also, when you link it into a library you actually compile it differently than when you compile it into an executable (the -package-name flag is different). So what we've done is to let executables depend on libraries. That makes the sharing explicit. At some point I also want to add support for private libs which would make this feature useful in more cases. Duncan