To answer my original question, here's a few ways to accomplish what I wanted with haskell Perl is still a lot faster than ghc -e, but I guess if you wanted speed you could compile first. ******************************************************************** thartman@linodewhyou:~/learning/haskell/UnixTools$ ls -l total 16 -rw-r--r-- 1 thartman thartman 2726 Dec 20 07:56 UnixTools.hs -rw-r--r-- 1 thartman thartman 82 Jan 7 07:18 echo.hs -rwxr--r-- 1 thartman thartman 790 Mar 4 05:02 oneliners.sh -rwxr--r-- 1 thartman thartman 646 Mar 4 04:18 oneliners.sh~ thartman@linodewhyou:~/learning/haskell/UnixTools$ ./oneliners.sh haskell, ghc -e pipe 16 real 0m1.652s user 0m0.600s sys 0m0.030s ********** haskell, hmap pipe 16 real 0m1.549s user 0m0.410s sys 0m0.200s ********** haskell, two pipes 16 real 0m2.153s user 0m0.900s sys 0m0.370s ********** perl, two pipes 16 real 0m0.185s user 0m0.010s sys 0m0.100s thartman@linodewhyou:~/learning/haskell/UnixTools$ thartman@linodewhyou:~/learning/haskell/UnixTools$ cat oneliners.sh hmap (){ ghc -e "interact ($*)"; } hmapl (){ hmap "unlines.($*).lines" ; } hmapw (){ hmapl "map (unwords.($*).words)" ; } function filesizes () { find -maxdepth 1 -type f | xargs du } echo haskell, ghc -e pipe time filesizes | ghc -e 'interact $ (++"\n") . show . sum . map ( ( read :: String -> Integer ) . head . words ) . lines ' echo "**********" echo haskell, hmap pipe time filesizes | hmap '(++"\n") . show . sum . map ( ( read :: String -> Integer ) . head . words ) . lines' echo "**********" echo haskell, two pipes time filesizes | hmapl "map ( head . words )" | hmap '(++"\n") . show . sum . map ( read :: String -> Integer ) . lines' echo "**********" echo perl, two pipes time filesizes | perl -ane 'print "$F[0]\n"' | perl -e '$sum += $_ while <>; print "$sum\n"' 2007/3/2, Thomas Hartman <tphyahoo@gmail.com>:
Okay, I am aware of
http://haskell.org/haskellwiki/Simple_unix_tools
which gives some implementation of simple unix utilities in haskell.
But I couldn't figure out how to use them directly from the shell, and of course that's what most readers will probably wnat.
Or let me put it another way.
Is there a way to do
find -maxdepth 1 -type f | xargs du | perl -ane 'print "\$F[0]\n"' | perl -e '$sum += $_ while <>; print "$sum\n"'
as a shell command that idiomatically uses haskell?
For non-perlers, that sums up the disk usage of all files in the current directory, skipping subdirs.
print "\$F[0]\n
looks at the first (space delimited) collumn of output.
perl -e '$sum += $_ while <>; print "$sum\n"'
, which is I guess the meat of the program, sums up all the numbers spewed out of the first column, so in the end you get a total.
So, anyone out there want to establish a haskell one liner tradition?
:)
thomas.