Instruções
Neste exercício, a tua tarefa é escrever código que devolva a letra da canção: "The Twelve Days of Christmas".
"The Twelve Days of Christmas" é uma conhecida canção de Natal inglesa.
Cada estrofe seguinte da canção baseia-se na anterior.
A letra que o teu código devolve deve corresponder exatamente ao texto completo da canção apresentado 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
Precisas de implementar a função recite, que produz a letra de
'The Twelve Days of Christmas'. Podes usar a assinatura fornecida
se tiveres dúvidas sobre os tipos, mas não deixes que isso restrinja a tua criatividade.
Este exercício trabalha com dados textuais. Por razões históricas, o tipo String do
Haskell é sinónimo de [Char], uma lista de carateres. Para um tratamento mais
eficiente de dados textuais, podes usar o tipo Text.
Como extensão opcional deste exercício, podes
import qualified Data.Text as T
import Data.Text (Text)
- escrever, por exemplo,
recite :: Int -> Int -> [Text] e referir os
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.
