我用 macports 安装 wxWidgets 然后运行命令：sudo cabal install wx其中输出包括：
/bin/sh: wxdirect: command not found
/bin/sh: wxdirect: command not found
/bin/sh: wxdirect: command not found
/bin/sh: wxdirect: command not found
Configuring wxcore-0.12.1.6...
setup: Missing dependency on a foreign library:
* Missing C library: wx_macu-2.8
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:
wx-0.12.1.6 depends on wxcore-0.12.1.6 which failed to install.
wxcore-0.12.1.6 failed during the configure step. The exception was:
ExitFailure 1
当我使用这个命令时，我得到了同样的错误：sudo cabal install wx --extra-include-dirs=/opt/local --extra-lib-dirs=/opt/local。如何安装 wx_macu-2.8，或者做我需要做的事情来解决这个问题？