I got this error installing readline (I really was installing lambdabot, it depends on readline): Configuring readline-1.0.1.0... checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... 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 GNUreadline.framework... checking for readline... yes checking for rl_readline_version... yes checking for rl_begin_undo_group... yes checking for rl_erase_empty_line... yes checking for rl_free_undo_list... yes checking for rl_completion_word_break_hook in -lreadline... yes configure: creating ./config.status config.status: creating config.mk config.status: creating readline.buildinfo config.status: creating include/HsReadlineConfig.h cabal: Missing dependency on a foreign library: * Missing header file: HsReadline.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. cabal: Error: some packages failed to install: lambdabot-4.2.2.1 depends on readline-1.0.1.0 which failed to install. readline-1.0.1.0 failed during the configure step. The exception was: exit: ExitFailure 1 This is on Leopard, with GNUreadline installed. As far as I see, HSReadline is an internally generated header in readline-1.0.1.0, how possibly cabal may be missing it? I got nothing with google, only that readline seems to be problematic on OSX. PS: I just installed cabal-install in ~/.cabal, it installs other packages without fuss (gsl-random being an exception, but it may be the GSL part...). Any help welcome! -- happy hacking... man