Hi guys, Just wanted to report on the steps/hacks to a successful build of GHC HEAD on OS X 10.9 thanks to help from Carter Schonwald and Austin Seipp. 1) I installed LLVM 3.4 brew install llvm --with-clang --HEAD 2) I used this build.mk: HADDOCK_DOCS = NO BUILD_DOCBOOK_HTML = NO BUILD_DOCBOOK_PS = NO BUILD_DOCBOOK_PDF = NO SPLIT_OBJS = NO INTEGER_LIBRARY = integer-simple 3) Austin let me know I needed to pass "-x assembler-with-cpp" to clang when in preprocessor mode, so I wrote a wrapper clang.hs, compiled it, put it in my path, and changed /usr/local/lib/ghc-7.6.2/settings to use it. (it also passes some flags Carter suggested, along with extra include flags, which were necessary as of a couple weeks ago but might have been fixed in the newer DPs) https://gist.github.com/lukexi/e11668ced04524564a8b 4) I used ./configure --with-gcc=clang (where clang is the wrapper script above) 5) "inplace/bin/mkdirhier" bootstrapping/. failed mysteriously, so I manually created bootstrapping/ in the ghc build dir. 6) DTrace failed with an "unsupported compiler" error during compilation, so I killed that section in configure.ac # if test -n "$DtraceCmd"; then # if test "x$TargetOS_CPP-$TargetVendor_CPP" = "xdarwin-apple" -o "x$TargetOS_CPP-$TargetVendor_CPP" = "xsolaris2-unknown"; then # HaveDtrace=YES # fi # fi 7) I got the error: libraries/integer-simple/GHC/Integer/Type.hs:836:50: Not in scope: '.' libraries/integer-simple/GHC/Integer/Type.hs:847:67: Not in scope: '.' I hacked through this by manually find-and-replacing WORD_SIZE_IN_BITS with 64 in Type.hs. make && make install then ran to completion and some simple test programs seem to compile and run fine. Cheers Luke