Re: [Haskell-cafe] Java or C to Haskell

How about something like this? import Data.List findMatch xs ys k = lookup k . concat $ zipWith zip (substrings xs) (substrings ys) where substrings = nonempty . map (nonempty . inits) . tails where nonempty = filter (not . null) On 20/09/06, Matthias Fischmann wrote:

... and if you want to search strings not single characters:

findmatch s t e = take m . drop n $ t where m' = length e (n, m) = f 0 s f i s | take m' s == e = (i, m') | null s = (0, 0) | otherwise = f (i+1) (tail s)

findmatch "asdfasdf" "asdfxvdf" "fas" == "fxv"

(this one skips equality checks before *and* after the match. feel free post the necessary modifications. :)

matthias

On Wed, Sep 20, 2006 at 02:22:29AM -0700, Carajillu wrote:

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To: haskell-cafe@haskell.org From: Carajillu Date: Wed, 20 Sep 2006 02:22:29 -0700 (PDT) Subject: Re: [Haskell-cafe] Java or C to Haskell

Yes, they must be equal the whole way, I like this recursive solution :)

Ketil Malde-3 wrote:

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Carajillu writes:

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compare function just compares the two lists and return true if they are equal, or false if they are not.

...

find_match "4*h&a" "4*5&a" 'h' ----> returns '5' (5 matches with the h) find_match "4*n&s" "4dhnn" "k" ----> returns '' (no match at all - lists are different anyway)

Must they be equal the whole way, or just up to the occurrence of the searched-for character?

find_match (x:xs) (y:ys) c | x==c = Just y | x/=y = Nothing | True = find_match xs ys c find_match [] [] _ = Nothing

Or, to check the whole list:

find_match (x:xs) (y:ys) c | x==c && xs == ys = Just y | x/=y = Nothing | True = find_match xs ys c find_match [] [] _ = Nothing

-k

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