Re: [Haskell-cafe] Minimizing cascading rebuilds

Optimizations shouldn't matter here: the problems there are caused by inlining, and if this data were short enough to get inlined then it also wouldn't be causing problems. Although I should note that ByteString "literals" aren't actually literals in the way the OP thinks, and this will also cause problems. The external data file is actually preferable for this reason. On Thu, Mar 29, 2018 at 1:25 AM, Dan Burton wrote:

I don't believe this is currently possible with ghc, due to the way ghc handles optimizations. I would love to be proven wrong on that.

On Wed, Mar 28, 2018, 22:11 ☂Josh Chia (謝任中) wrote:

...

Hi,

In my project, I have multiple packages. One of the packages, packageA, is very fundamental and depended on directly and indirectly by almost all the other packages. It has functions that use some hard-coded data (a ByteString top-level variable) also defined within packageA.

This hard-coded data is appended regularly, causing packageA to be rebuilt and thus almost all the other packages to be rebuilt, and building takes a painfully long time. I know I can move this hard-coded data to a file that's read at run-time, but that means one more item to plumb in at run-time (where to find the file), and IO (preventing the functions from being pure), so I would like to keep it hard-coded.

Is there an elegant way to prevent or minimize the cascading rebuild of the dependent packages just because the hard-coded data in packageA changed?

For analogy, in C or C++, source code gets compiled to .o files, one for each .cpp source file. Multiple .o files get linked into executables. So, unless the interface (.hpp files) also change, an implementation (.cpp file) change does not cause dependents to be recompiled to get new .o files, although dependent executables get relinked. I'm not familiar with the compilation and linking logic in GHC so maybe it has additional complications.

BTW, I'm using stack, in case it makes any difference to the nature of the problem.

Josh _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.

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