[Haskell-cafe] doctest (Was: Batteries included (Was: GHC is a monopoly compiler))

[Richard A. O'Keefe]

m% cabal install doctest
cabal: /usr/bin/ar: permission denied
m% file /usr/bin/ar; ls -l /usr/bin/ar
/usr/bin/ar: Mach-O 64-bit executable x86_64
-rwxr-xr-x  1 root  wheel  18160 14 Jan  2016 /usr/bin/ar

What am I doing wrong?