diff --git a/src/Chapter1.hs b/src/Chapter1.hs index 406deeaca..e527a55ac 100644 --- a/src/Chapter1.hs +++ b/src/Chapter1.hs @@ -209,31 +209,31 @@ So, the output in this example means that 'False' has type 'Bool'. > Try to guess first and then compare your expectations with GHCi output >>> :t True - +True :: Bool >>> :t 'a' - +'a' :: Char >>> :t 42 - +42 :: Num a => a A pair of boolean and char: >>> :t (True, 'x') - +(True, 'x') :: (Bool, Char) Boolean negation: >>> :t not - +not :: Bool -> Bool Boolean 'and' operator: >>> :t (&&) - +(&&) :: Bool -> Bool -> Bool Addition of two numbers: >>> :t (+) - +(+) :: Num a => a -> a -> a Maximum of two values: >>> :t max - +max :: Ord a => a -> a -> a You might not understand each type at this moment, but don't worry! You've only started your Haskell journey. Types will become your friends soon. @@ -301,43 +301,43 @@ expressions in GHCi functions and operators first. Remember this from the previous task? ;) >>> 1 + 2 - +3 >>> 10 - 15 - +-5 >>> 10 - (-5) -- negative constants require () - +15 >>> (3 + 5) < 10 - +True >>> True && False - +False >>> 10 < 20 || 20 < 5 - +True >>> 2 ^ 10 -- power - +1024 >>> not False - +True >>> div 20 3 -- integral division - +6 >>> mod 20 3 -- integral division remainder - +2 >>> max 4 10 - +10 >>> min 5 (max 1 2) - +2 >>> max (min 1 10) (min 5 7) - +5 Because Haskell is a __statically-typed__ language, you see an error each time you try to mix values of different types in situations where you are not @@ -428,7 +428,7 @@ task is to specify the type of this function. >>> squareSum 3 4 49 -} - +squareSum :: Int -> Int -> Int squareSum x y = (x + y) * (x + y) @@ -449,7 +449,7 @@ Implement the function that takes an integer value and returns the next 'Int'. function body with the proper implementation. -} next :: Int -> Int -next x = error "next: not implemented!" +next x = x + 1 {- | After you've implemented the function (or even during the implementation), you @@ -490,7 +490,8 @@ Implement a function that returns the last digit of a given number. whether it works for you! -} -- DON'T FORGET TO SPECIFY THE TYPE IN HERE -lastDigit n = error "lastDigit: Not implemented!" +lastDigit :: Int -> Int +lastDigit n = mod (abs n) 10 {- | @@ -520,7 +521,7 @@ branches because it is an expression and it must always return some value. satisfying the check will be returned and, therefore, evaluated. -} closestToZero :: Int -> Int -> Int -closestToZero x y = error "closestToZero: not implemented!" +closestToZero x y = if ((min (abs x) (abs y)) == (abs x)) then x else y {- | @@ -554,7 +555,11 @@ value after "=" where the condition is true. Casual reminder about adding top-level type signatures for all functions :) -} -mid x y z = error "mid: not implemented!" +mid :: Int -> Int -> Int -> Int +mid x y z + | ((x <= y) && (x >= z)) || ((x <= z) && (x >= y)) = x + | (y <= x) && (y >= z) || ((y <= z) && (y >= x))= y + | otherwise = z {- | =⚔️= Task 8 @@ -568,7 +573,10 @@ True >>> isVowel 'x' False -} -isVowel c = error "isVowel: not implemented!" +isVowel :: Char -> Bool +isVowel c + | ((c == 'a') || (c == 'e') || (c == 'i') || (c == 'o') || (c == 'u')) = True + | otherwise = False {- | @@ -631,8 +639,17 @@ Implement a function that returns the sum of the last two digits of a number. Try to introduce variables in this task (either with let-in or where) to avoid specifying complex expressions. -} +sumLast2 :: Int -> Int +sumLast2 n = nextLastDigit n + lastDigit n + where + last2Digits :: Int -> Int + last2Digits y = mod (abs y) 100 + + nextLastDigit :: Int -> Int + nextLastDigit x = div (last2Digits x) 10 -sumLast2 n = error "sumLast2: Not implemented!" + lastDigit :: Int -> Int + lastDigit z = mod (last2Digits z) 10 {- | @@ -652,8 +669,8 @@ Implement a function that returns the first digit of a given number. You need to use recursion in this task. Feel free to return to it later, if you aren't ready for this boss yet! -} - -firstDigit n = error "firstDigit: Not implemented!" +firstDigit :: Int -> Int +firstDigit n = if (div (abs n) 10) > 0 then firstDigit (div (abs n) 10) else (mod (abs n) 10) {-