On 2005 May 16 Monday 08:00, Gracjan Polak wrote: > Ketil Malde wrote: > > While the result isn't exactly the same, I suspect > > using isPrefixOf and tails would be more efficient. > > I need the data before and including my needle.
When the haystack gets large, the beautiful find (isSuffixOf "needle") (inits "haystack") is quite inefficient where it uses isSuffixOf searching longer and longer strings. You can get efficiency, the desired data, and deal with infinite strings by using a function that is like 'inits' but which returns the initial strings in reversed order. reversed_inits = scanl (flip (:)) "" find (isPrefixOf (reverse "needle")) (reversed_inits "haystack") _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
