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August 2015

3 participants
2 discussions

Discovery of source dependencies without --make
by Lars Hupel 13 Dec '15

13 Dec '15

(cross-posted from [haskell-cafe]) Hi, I've got a problem in our – admittedly complex – build process. We're running an automated grading system for student-submitted homework exercises. The compilation proceeds in stages: 1) Compile a library file, marked as trustworthy 2) Compile student submissions using Safe Haskell, able to access a whitelisted set of packages and the previously compiled library files 3) Compile the test suite 4) Link everything together into an executable The invocation is similar to this: ghc -c -outputdir "$OUT" -XTrustworthy Library.hs ghc -c -outputdir "$OUT" -i"$OUT" -XSafe "$SUBMISSION" ghc -c -outputdir "$OUT" -i"$OUT" Test_Suite.hs ghc -outputdir "$OUT" -i"$OUT" -o "$OUT/runner" The second stage works well under the assumption that there's just one single submitted file. If there's more than one, I need to specify them in topological order wrt their module dependencies. Consider two simple modules: A.hs > module A where > > import B > import Library B.hs > module B where Invoking GHC with "A.hs" "B.hs" will fail: A.hs:3:1: Failed to load interface for ‘B’ My naive attempt at solving that problem was to just insert "--make" into the compiler flags. No luck, because according to [1, §4.7.3], "--make" will only look at source files and will ignore the "Library.hi" file from the previous compilation stage. If I give the path to "Library.hs" as well, GHC insists on recompiling it with changed flags ("-XSafe" instead of "-XTrustworthy"). Reading a bit further, I discovered the '-M' flag, however, not only does it output Makefile-formatted output, it also ignores .hi files. Is there any way to get the dependency discovery of '--make' without the rest? I know I could probably make it work if I made a package out of the first build stage, but I really want to avoid that in order to not increase the build complexity even further. Cheers Lars [1] <https://downloads.haskell.org/~ghc/7.6.3/docs/html/users_guide/separate-com…>

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simultaneous ghc versions
by Evan Laforge 03 Aug '15

03 Aug '15

The recent release of ghc 7.10.2 reminded me of something I meant to ask about a long time ago. Most of the binaries ghc installs are versioned (x linked to x-7.10.2), with some exceptions (hpc and hsc2hs). Shouldn't they all be versioned? Also, 'haddock' is inconsistent with all the rest, in that it's haddock linked to haddock-ghc-7.10.2. I've long used a few shell scripts (recently upgraded to python) to manage ghc installs. A 'set' which creates symlinks to make a particular version current, and an 'rm' to remove all traces of a version. But due to the inconsistency, I have to remember to run "fix" first, which moves the unversioned binaries to versioned names. As an aside, I have three scripts I use all the time: set version, remove version, and remove library. Come to think of it, shouldn't ghc include this, instead of everyone creating their own shell scripts by hand?

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