Re: [Haskell-beginners] homogeneous value list

Should it? I tried to explain it, but if you are not convinced just give it a try.

Guess what? You do not need the special case for [], because "all _ [] = True" allways. So if the list is empty, it won't even try evaluating "first".

On 12 March 2010 14:25, Salil Wadnerkar wrote:

On Fri, Mar 12, 2010 at 10:21 PM, Ozgur Akgun wrote:

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Another boring variant from me then.

isHomogeneous xs = all (first==) xs where first = head xs

Shouldn't head xs give an exception on an empty list?

...

Guess what? You do not need the special case for [], because "all _ [] = True" allways. So if the list is empty, it won't even try evaluating "first".

Cheers,

On 12 March 2010 14:08, Daniel Fischer wrote:

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Am Freitag 12 März 2010 14:41:11 schrieb Daniel Fischer:

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isHomogeneous :: Eq a => [a] -> Bool isHomogeneous [] = True isHomogeneous (x:xs) = all (== x) xs

Variant, getting rid of the special case for an empty list:

isHomogeneous :: Eq a => [a] -> Bool isHomogeneous xs = and (zipWith (==) xs (drop 1 xs)) _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

-- Ozgur Akgun

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-- Ozgur Akgun