yafc won't install on 10.6 due to an "architecture mismatch"

[looris@…]

looris@XPLOMAC:~ $ sudo port install yafc
Error: Cannot install yafc for the arch(s) 'x86_64' because
Error: its dependency readline is only installed for the arch 'i386'
Error: and the configured universal_archs 'i386 ppc' are not sufficient.
Error: Unable to execute port: architecture mismatch

looris@XPLOMAC:~ $ uname -a
Darwin XPLOMAC.local 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun  7 16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386 i386

looris@XPLOMAC:~ $ port version
Version: 2.0.3

[ryandesign (Ryan Carsten Schmidt)]

Change universal_archs in macports.conf to the correct value for Snow Leopard -- x86_64 i386 -- then for every port that you already installed with the universal variant, rebuild it. You may have other old values in macports.conf; take some time to compare macports.conf.default with your macports.conf and adopt any new values you haven't deliberately changed.

[ryandesign (Ryan Carsten Schmidt)]

If you upgraded to Snow Leopard from an earlier OS X version, and haven't since then uninstalled and reinstalled all ports, you should do that; see wiki:Migration.