[Haskell-cafe] Re: wanted: haskell one-liners (in the perl sense of one-liners)

[Donald Bruce Stewart]

There's some nice one liners bundled with h4sh:

    http://www.cse.unsw.edu.au/~dons/h4sh.html

For example:

    http://www.cse.unsw.edu.au/~dons/h4sh.txt

If you recall, h4sh is a set of unix wrappers to the list library.
I still use them everyday, though probably should put out a new release
soon.

-- Don


tphyahoo:
> 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 at 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 at 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 at linodewhyou:~/learning/haskell/UnixTools$
> 
> 
> thartman at 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 at 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.
> >
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