AulaP2 PLP

unitaryN :: Int ->[[Int]]
unitaryN n=[[ if i==j then 1 else 0 |i <- [1..n]]| j<-[1..n]]

myNu :: Int -> String
myNu 5 = "Happy Child"
myNu 10 = "Some troubles?"
myNu 17 = "I want to travel"
myNu 20 = "The world is mine"
myNu x = "I do not know this number"

age :: Int -> String
age x
   | x<=0 =  "Wrong age!"
   | x< 7 =  "Sweet child"
   | x<18 =  "Youth"
   | otherwise = "Work"

disc :: Double -> Double
disc r = pi*r*r

disc' r = pi*sq -- We can use prim '  on the name as have disc2 or 1
   where
   sq=r*r

disc'' r =
  let
  sq=r*r
  in pi*sq

--charN :: Int -> String -> Char
charN n s = s !! (n-1)

second (a,b,c) = b
second' (_,b,_) = b


pair [] _ = (0,0)
pair _ [] = (0,0)
pair x y = (head x, last y)

{-
Ex. 2.
=======
Define two lists: listA, listB;
listA is a list of 6 ordered pairs of strings - names and surnames of certain people;
listB consists of two-digit numbers with the digits of tens 3, 5 or 7 and the digits of unity 3 or 4.
a) Define the list named listA1 consisting only of the names from the list listA.
b) Define the list named listA2 consisting only of the surnames from the list listA.
c) Define the list named people - the list of  triples of all possible systems (name, surname, age), where the age is from listB.
-}
listA = [   ("Nicolas", "Mazard") , ("Manuel", "Curral")]

listA1' = map fst ListA
listB   = [10*a+b|a<-[3,5,7],b<-[3,4]]
--write ListA2
people = [(n,s,a)| n<-ListA1,s<-ListA2,q<-ListB]