Just some tidy ups of the previous
article, on implementing unix 'cat' in Haskell.
Firstly, several people wrote in to point out the bug in the -b option.
Rather than squeezing only blank lines, it would do more of a 'uniq'
kind of thing, squeezing all duplicates:
render Squeeze = map head. group
Rather than:
render Squeeze = map head. groupBy (\x y -> all (all isSpace) [x,y])
Secondly, the complete source is now available via darcs, with a cabal build system.
$ darcs get http://www.cse.unsw.edu.au/~dons/code/caths
Copying patch 2 of 2... done!
Applying patch 2 of 2... done.
Finished getting.
$ cd caths
$ runhaskell Setup.lhs configure --prefix=/home/dons
$ runhaskell Setup.lhs build
$ runhaskell Setup.lhs install
And you're done.
Next week
We'll look at writing an SMP-parallel, bytestring-based url checker in Haskell:
$ urlcheck ph-3-redux.txt
Found 0 broken links. Checked 4 links (4 unique) in 1 file.
Search time 0 secs
/home ::
/haskell ::
permalink ::
rss
