anchor.diff:      "--with-skk"
       "--with-x"
       "--with-xft"
  +    "--with-expat=${expat.dev}"
     ]
     ++ optional withAnthy "--with-anthy-utf8"
     ++ optional withGtk2 "--with-gtk2"
  
positive.code:     cmake
      m17n_lib
      m17n_db
    ]
    ++ optional withAnthy anthy
    ++ optional withGtk2 gtk2
  
negative.code: { stdenv, fetchurl, intltool, pkgconfig, cmake
  , ncurses, m17n_lib, m17n_db, expat
  , withAnthy ? true, anthy ? null
  , withGtk ? true
  , withGtk2 ? withGtk, gtk2 ? null
  