solve Lecture1 #1
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| @@ -54,7 +55,8 @@ Explanation: @sumOfSquares 3 4@ should be equal to @9 + 16@ and this | |||
| is 25. | |||
| -} | |||
| -- DON'T FORGET TO SPECIFY THE TYPE IN HERE | |||
| sumOfSquares x y = error "TODO!" | |||
| sumOfSquares :: Num a => a -> a -> a | |||
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Num is explained in the following lectures, so you are one step ahead 😸
In here Int -> Int -> Int or Integer -> Integer -> Integer would also work, as a more specific type 🙂
| lastDigit n = error "lastDigit: Not implemented!" | ||
| lastDigit :: Integral a => a -> a | ||
| lastDigit n = | ||
| mod (abs n) 10 |
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Absolutely correct 👍🏻
Alternatively, you can use the infix form of a function by putting it inside backticks 🙂
| mod (abs n) 10 | |
| abs n `mod` 10 |
| lowerAndGreater n list = | ||
| iter n list 0 0 | ||
| where | ||
| iter n [] lower greater = show n |
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I see that the number n that you pass in recursive calls doesn't change. You always pass the same number. In that case, you can remove this extra argument and use n from the function instead. It's possible because functions in where can see all the arguments of the top-level function 🔍
| lowerAndGreater n list = error "TODO" | ||
| lowerAndGreater :: (Show a, Ord a) => a -> [a] -> [Char] | ||
| lowerAndGreater n list = | ||
| iter n list 0 0 |
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Numeric literals in Haskell are polymorphic. That's why you have lots of GHC warnings about defaulting constraints.
To fix this, you can either specify the type of iter explicitly or specialize literals here
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thanks for great instuctions.
Actually I use HLS to specify types and formmating.
Here refctoring iter
iter [] lower greater =
show n
++ " is greater than "
++ show lower
++ " elements and lower than "
++ show greater
++ " elements"
iter (h : t) lower greater
| h < n = iter t (lower + 1) greater
| h > n = iter t lower (greater + 1)
| otherwise = iter t lower greaterThere was a problem hiding this comment.
Looks great! And yes, HLS can be really helpful 👏🏻
Co-authored-by: Dmitrii Kovanikov <[email protected]>
Solutions for Lecture 1
cc @chshersh