Pattern Match Failure in List in Haskell -

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i have 1 problem pattern matching. when give input (x:y:ys) list containing 3 elements, hugs complain there is: pattern match failure. guess problem here

takenearestones agent (y:ys) (x:nearestones)

because fails match 3 elements list containing 2 elements

this full code:

takenearestones agent (x:y:ys) nearestones             | first == second =  takenearestones agent (y:ys) (x:nearestones)             | otherwise = (x:nearestones)         first=(manhattandistance x (agentcoord agent))               second=(manhattandistance y (agentcoord agent)

how can overcome this? in advance

since function recursive , decreasing list, going work you're way down list of 1 element, in case match fail. can fix adding case of function handles feel appropriate

something like

takenearestones agent [x] nearestones = dosomething takenearestones agent []  nearestones = dosomethingelse

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