ficha2

dobros :: [Float] -> [Float]
dobros [] = []
dobros [x] = [2*x]
dobros (x:y) = 2*x : (dobros y)

numOcorre :: Char -> String -> Int
numOcorre x [] = 0
numOcorre x (y:z) = if x == y then 1 + numOcorre x z else numOcorre x z

positivos :: [Int] -> Bool
positivos [x] = if x<0 then False else True
positivos (x:y) = if x<0 then False else positivos y

soPos :: [Int] -> [Int]
soPos [] = []
soPos (x:y) = if x <= 0 then soPos y else x:(soPos y)

--soNeg :: [Int] -> [Int]
--soNeg [] = []
--soNeg (x:y) = if x >= 0 then soNeg y else x:(soNeg y)

somaNeg :: [Int] -> Int
somaNeg [] = 0
somaNeg (x:y) =  if x < 0 then x + somaNeg y else somaNeg y

tresUlt :: [a] -> [a]
tresUlt [] = []
tresUlt (x:y) = if length (x:y) <= 3 then (x:y) else tresUlt y

segundos :: [(a,b)] -> [b]
segundos [] = []
segundos (x,y) = y:segundos (x:y)