Practica 1

p1/Ejercicios.hs

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+module Ejercicios where
+import Data.Char
+
+-- EJERCICIOS SOBRE TIPOS BASICOS
+
+-- Ejercicio 1
+siguienteLetra :: Char -> Char
+siguienteLetra 'z' = 'a'
+siguienteLetra 'Z' = 'A'
+siguienteLetra a = chr ((ord a) + 1)
+
+-- Ejercicio 2
+sumatorio :: Int -> Int -> Int
+sumatorio a b
+    | a == b = a
+    | otherwise = a + (sumatorio (a + 1) b)
+
+-- Ejercicio 3
+productorio :: Int -> Int -> Int
+productorio a b
+    | a == b = a
+    | otherwise = a * (productorio (a + 1) b)
+
+-- Ejercicio 4
+maximo :: Int -> Int -> Int
+maximo a b
+    | signum (a - b) == 1 = a
+    | otherwise = b
+
+-- Ejercicio 5
+fact :: Int -> Int
+fact 0 = 1
+fact n = n * fact (n - 1)
+
+-- Ejercicio 6
+sumaFacts :: Int -> Int
+sumaFacts 0 = fact 0
+sumaFacts n = fact n + sumaFacts (n - 1)
+
+-- EJERCICIOS SOBRE TIPOS LISTAS
+
+-- Ejercicio 1
+sumaPares :: [(Int, Int)] -> [Int]
+sumaPares [] = []
+sumaPares (x:xs) = fst x + snd x : sumaPares xs
+-- Alternativa sumaPares ((x, y):xs) = x+y : sumaPares xs
+
+-- Ejercicio 2
+cab :: [a] -> a
+cab (x:xs) = x
+cola :: [a] -> a
+cola (x:xs)
+    | xs == [] = x
+    | otherwise = cola xs
+
+-- Ejercicio 3
+divisores :: Int -> [Int]
+divisores n = [i | i <- [1..n], mod n i == 0]
+
+-- Ejercicio 4
+enLista :: Int -> [Int] -> Bool
+enLista n [] = False
+enLista n (x:xs)
+    | n == x = True
+    | otherwise = enLista n xs
+
+-- Ejercicio 5
+replace :: [Int] -> Int -> Int -> [Int]
+replace [] n p = []
+replace (x:xs) n p
+    | x == n = p : replace xs n p
+    | otherwise = x : replace xs n p
+
+-- Ejercicio 6
+count :: Int -> [Int] -> Int
+count n [] = 0
+count n (x:xs)
+    | n == x = 1 + count n xs
+    | otherwise = count n xs
+
+-- Ejercicio 7
+multiplosCinco :: [Int]
+multiplosCinco = [x * 5 | x <- [1..]] -- Listas intensionales multiplicando
+multiplosCinco4 :: [Int]
+multiplosCinco4 = [x | x <- [1..], mod x 5 == 0] -- Listas intensionales comprobando
+multiplosCinco2 :: [Int]
+multiplosCinco2 = map (* 5) [1..] -- Orden superior (map)
+multiplosCinco3 :: [Int]
+multiplosCinco3 = filter (\x -> mod x 5 == 0) [1..] -- Orden superior (filter)
+
+-- Ejercicio 8
+cogeMayus :: [Char] -> [Char]
+cogeMayus [] = []
+cogeMayus (x:xs)
+    | isUpper x = x : cogeMayus xs
+    | otherwise = cogeMayus xs

p1/Errortipos.hs

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+module Errortipos where
+
+-- Causa error de tipos
+-- main = f (0, 'a')
+-- Expresion corregida
+main = f('a', 0)
+
+f :: (Char, Int) -> String
+f (c, i) = [c] ++ show i

p1/Hello.hs

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+module Hello where
+
+hello n = concat(replicate n "hello ")
+hello :: Int -> [Char]

p1/Long.hs

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+module Long where
+
+long [] = 0
+long (x:t) = 1 + long t
+

p1/Power1.hs

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+module Power1 where
+
+power1 :: Int -> Int -> Int
+
+power1 _ 0 = 1
+power1 n t = n * power1 n (t - 1)

p1/Power2.hs

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+module Power1 where
+
+power2 :: Int -> Int -> Int
+
+power1 _ 0 = 1
+power1 n t 
+	| even t = power2 (n * n) (div t 2)
+	| otherwise = n * power2 (n * n) (div t 2)

p1/Toma.hs

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+module Toma where
+
+toma :: Int -> [a] -> [a]
+toma 0 _ = []
+toma n (x:t) = x : toma (n - 1) t