99 questions/Solutions/22

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Revision as of 05:22, 20 November 2010 by Drb226 (talk | contribs) (slightly modified the version with guards so that it will make backwards ranges too)

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Create a list containing all integers within a given range.

range x y = [x..y]


range = enumFromTo


range x y = take (y-x+1) $ iterate (+1) x


range start stop
    | start > stop  = reverse (range stop start)
    | start == stop = [stop]
    | start < stop  = start:range (start+1) stop

Since there's already syntactic sugar for ranges, there's usually no reason to define a function like 'range' in Haskell. In fact, the syntactic sugar is implemented using the enumFromTo function, which is exactly what 'range' should be.