Instruções
Sua tarefa neste exercício é escrever um código que retorne a letra da música: "The Twelve Days of Christmas."
"The Twelve Days of Christmas" é uma canção natalina inglesa comum.
Cada estrofe seguinte da música se baseia na estrofe anterior.
A letra que seu código retorna deve corresponder exatamente ao texto completo da música mostrado abaixo.
Letra
On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
Dicas
Você precisa implementar a função recite, que gera a letra de 'The Twelve Days of Christmas'. Você pode usar a assinatura fornecida se não tiver certeza sobre os tipos, mas não deixe que ela limite sua criatividade.
Este exercício trabalha com dados textuais. Por razões históricas, o tipo String de Haskell é sinônimo de [Char], uma lista de caracteres. Para lidar com dados textuais de forma mais eficiente, é possível usar o tipo Text.
Como uma extensão opcional deste exercício, você pode
import qualified Data.Text as T
import Data.Text (Text)
- escrever, por exemplo,
recite :: Int -> Int -> [Text] e se referir aos
combinadores de Data.Text como, por exemplo, T.pack.
- consultar a documentação de
Data.Text.
- substituir todas as ocorrências de
String por Text em TwelveDays.hs, ou seja:
recite :: Int -> Int -> [Text]
Esta parte é totalmente opcional.
