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Questions and Answers
What does the function double calculate when applied to the number 2?
What does the function double calculate when applied to the number 2?
If you define a function such that sum [x] = x for any number x, what does this imply about the behavior of the function sum?
If you define a function such that sum [x] = x for any number x, what does this imply about the behavior of the function sum?
What is the expected output of the function product when applied to the list [2,3,4]?
What is the expected output of the function product when applied to the list [2,3,4]?
To modify the function qsort to produce a reverse sorted list, how should the comparison logic be adjusted?
To modify the function qsort to produce a reverse sorted list, how should the comparison logic be adjusted?
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In functional programming, what is the main characteristic of the functions sum and product described in the exercises?
In functional programming, what is the main characteristic of the functions sum and product described in the exercises?
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Study Notes
Haskell Report
- The Haskell Report is a document that provides a formal specification of the Haskell programming language.
- It is freely available for download on the Haskell website.
Chapter Remarks
- There are resources available that provide more detailed historical accounts of functional languages and the development of Haskell.
Exercise 1
- The function
doubletakes a number as input and returns the result of multiplying that number by 2. - An alternative implementation would be to use the addition operator:
double x = x + x.
Exercise 2
- The function
sumtakes a list of numbers as input and returns the sum of all the numbers in the list. - The equation
sum [x] = xis true for any numberxbecause the list contains only one element, which isx.
Exercise 3
- The function
productshould take a list of numbers as input and return the product of all the numbers in the list. - An example implementation is
product [] = 1; product (x:xs) = x * product xs. - Using this implementation,
product [2,3,4] = 24because2 * (3 * (4 * 1)) = 24.
Exercise 4
- The function
qsortsorts a list in ascending order. - To modify
qsortto sort a list in descending order, you would need to reverse the order of elements in the list. - This can be achieved by reversing the list before sorting it or by reversing the order of elements while sorting.
### Exercise 5
- Replacing
<=with>=in the definition of the functionqsortwould reverse the order in which elements are compared. - This would result in the function sorting the list in descending order instead of ascending order.
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Description
This quiz focuses on exercises related to the Haskell programming language, including functions for doubling a number, summing a list, and calculating the product of a list. It serves as a practical application of Haskell concepts and helps reinforce understanding of functional programming principles.
