OK -- I've managed to build it as follows. 1. Got the readline from the source at ftp.gnu.org. Always fun to ftp to the mothership, got the patches while at it. Always fun to remember where to cd to patch and which -p level to supply. 2. Built and installed readline 6.004 with default /usr/local prefix. 3. In the readline-1.0.1.0, manually ran ./configure --with-readline-includes=/usr/local/include --with-readline-libraries=/usr/local/lib 4. runghc Setup.hs build # no runghc Setup.hs configure, messes things right back! 5. sudo runghc Setup.hs install The only difference with cabal install is that (5) installs in /usr/local, but apparently subsequent cabal install modules which need readline finds it, even though installing in ~/.cabal/. I wonder if having multiple libreadline5.x.dylib and ...6... in /opt/local/lib, the residue from the previous MacPorts, some not deactivated, may confuse Cabal. In any case, installing things manually into /usr/local/ generally coexisted well with MacPorts for me, so this works for now. Cheers, Alexy