Hi Johan, I just tried compiling network-2.2.1.5 with GHC 6.12.1rc2 on Windows, under Cygwin. The failures I got were: $ runhaskell Setup build Setup.hs:3:0: Warning: In the use of `defaultUserHooks' (imported from Distribution.Simple): Deprecated: "Use simpleUserHooks or autoconfUserHooks, unless you need Cabal-1.2 compatibility in which case you must stick with defaultUserHooks" Preprocessing library network-2.2.1.5... Network\Socket.hsc: In function `main': Network\Socket.hsc:994: error: invalid application of `sizeof' to incomplete type `ucred' Network\Socket.hsc:994: error: invalid application of `sizeof' to incomplete type `ucred' Network\Socket.hsc:994: error: invalid application of `sizeof' to incomplete type `ucred' Network\Socket.hsc:999: error: `SO_PEERCRED' undeclared (first use in this function) Network\Socket.hsc:999: error: (Each undeclared identifier is reported only once Network\Socket.hsc:999: error: for each function it appears in.) Network\Socket.hsc:1000: error: dereferencing pointer to incomplete type Network\Socket.hsc:1001: error: dereferencing pointer to incomplete type Network\Socket.hsc:1002: error: dereferencing pointer to incomplete type compiling dist\build\Network\Socket_hsc_make.c failed command was: C:\ghc\ghc-6.12.1-rc2\mingw\bin\gcc.exe -c -D__GLASGOW_HASKELL__=612 -Iinclude -DCALLCONV=ccall -DBASE4 -IC:\ghc\ghc-6.12.1-rc2\base-4.2.0.0\include -IC:\ghc\ghc-6.12.1-rc2/include -IC:\ghc\ghc-6.12.1-rc2/include -IC:/ghc/ghc-6.12.1-rc2/lib/include/ dist\build\Network\Socket_hsc_make.c -o dist\build\Network\Socket_hsc_make.o I then tried the darcs version and got: $ runhaskell Setup configure Setup.hs:3:0: Warning: In the use of `defaultUserHooks' (imported from Distribution.Simple): Deprecated: "Use simpleUserHooks or autoconfUserHooks, unless you need Cabal-1.2 compatibility in which case you must stick with defaultUserHooks" Warning: defaultUserHooks in Setup script is deprecated. Configuring network-2.2.1.5... configure: WARNING: unrecognized options: --with-hc checking build system type... i686-pc-cygwin checking host system type... i686-pc-cygwin checking for gcc... gcc checking for C compiler default output file name... a.exe checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... .exe checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking for an ANSI C-conforming const... yes checking how to run the C preprocessor... gcc -E checking for grep that handles long lines and -e... /usr/bin/grep checking for egrep... /usr/bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking fcntl.h usability... yes checking fcntl.h presence... yes checking for fcntl.h... yes checking limits.h usability... yes checking limits.h presence... yes checking for limits.h... yes checking for stdlib.h... (cached) yes checking for sys/types.h... (cached) yes checking for unistd.h... (cached) yes checking winsock2.h usability... no checking winsock2.h presence... yes configure: WARNING: winsock2.h: present but cannot be compiled configure: WARNING: winsock2.h: check for missing prerequisite headers? configure: WARNING: winsock2.h: see the Autoconf documentation configure: WARNING: winsock2.h: section "Present But Cannot Be Compiled" configure: WARNING: winsock2.h: proceeding with the compiler's result configure: WARNING: ## ------------------------------------ ## configure: WARNING: ## Report this to libraries@haskell.org ## configure: WARNING: ## ------------------------------------ ## checking for winsock2.h... no checking ws2tcpip.h usability... no checking ws2tcpip.h presence... yes configure: WARNING: ws2tcpip.h: present but cannot be compiled configure: WARNING: ws2tcpip.h: check for missing prerequisite headers? configure: WARNING: ws2tcpip.h: see the Autoconf documentation configure: WARNING: ws2tcpip.h: section "Present But Cannot Be Compiled" configure: WARNING: ws2tcpip.h: proceeding with the compiler's result configure: WARNING: ## ------------------------------------ ## configure: WARNING: ## Report this to libraries@haskell.org ## configure: WARNING: ## ------------------------------------ ## checking for ws2tcpip.h... no checking wspiapi.h usability... no checking wspiapi.h presence... no checking for wspiapi.h... no checking arpa/inet.h usability... yes checking arpa/inet.h presence... yes checking for arpa/inet.h... yes checking netdb.h usability... yes checking netdb.h presence... yes checking for netdb.h... yes checking netinet/in.h usability... yes checking netinet/in.h presence... yes checking for netinet/in.h... yes checking netinet/tcp.h usability... yes checking netinet/tcp.h presence... yes checking for netinet/tcp.h... yes checking sys/socket.h usability... yes checking sys/socket.h presence... yes checking for sys/socket.h... yes checking sys/uio.h usability... yes checking sys/uio.h presence... yes checking for sys/uio.h... yes checking sys/un.h usability... yes checking sys/un.h presence... yes checking for sys/un.h... yes checking for readlink... yes checking for symlink... yes checking for struct msghdr.msg_control... yes checking for struct msghdr.msg_accrights... no checking for struct sockaddr.sa_len... no checking for in_addr_t in netinet/in.h... yes checking for SO_PEERCRED and struct ucred in sys/socket.h... yes checking for _head_libws2_32_a in -lws2_32... yes checking for getaddrinfo... no checking for getaddrinfo if WINVER is 0x0501... no checking for gai_strerror... no checking whether AI_ADDRCONFIG is declared... no checking whether AI_ALL is declared... no checking whether AI_NUMERICSERV is declared... no checking whether AI_V4MAPPED is declared... no checking for sendfile in sys/sendfile.h... no checking for sendfile in sys/socket.h... no checking for gethostent... no configure: creating ./config.status config.status: creating network.buildinfo config.status: creating include/HsNetworkConfig.h configure: WARNING: unrecognized options: --with-hc Setup: Missing dependency on a foreign library: * Missing header file: HsNet.h This problem can usually be solved by installing the system package that provides this library (you may need the "-dev" version). If the library is already installed but in a non-standard location then you can use the flags --extra-include-dirs= and --extra-lib-dirs= to specify where it is. I was really hoping for a Network package on GHC 6.12, as lots of my stuff depends (indirectly) on it. Is there anything I can do to help? Thanks, Neil