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--- fp:lab01-java-intro [2021/03/11 13:03]
pdmatei
+++ fp:lab01-java-intro [2021/03/11 14:50] (current)
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 ===== 1. A single function to implement all of them =====
-.1. Write a method that takes a list of integers and returns a new list with all elements multiplied by two.
+.1. Write a method that takes a list of **integers** and returns a new list with all elements multiplied by two.
-.2. Write a method that takes a list of doubles and returns a new list with all elements multiplied by two.
+.2. Write a method that takes a list of **doubles** and returns a new list with all elements multiplied by two.
 .3. Write a method that takes a list of integers and returns a new list with all the elements’ successors (i.e. the elements incremented by 1).
@@ Line 11: / Line 11: @@
 .4. Write a method that takes a list of integers and returns a new list of booleans indicating if an element is prime.
-.5. (Discussion) What is common among all previous implementations? Could a single //list function// (a more general function) be used to achieve all results? Starting from the **signatures** of the previous functions, write the **signature** for this general function which we will call **map**.
+.5. (Discussion) What is common among all previous implementations? Could a single //list function// (a more general function) be used to achieve all results? Starting from the **signatures** of previous functions, write the **signature** for this general function which we will call **map**.
+.6. (Discussion) How can we pass **functions** as parameter (to another function) in Java? Consider **unary** functions of the form: $math[f : A \rightarrow B] (where $math[A] and $math[B] are generic).
+.7. (!) Write an implementation for ''map'' and use ''map'' to solve 1.4.
+===== 2. Throwing out elements ... =====
+.1. Write a method that takes a list of integers and returns a new list containing only even elements.
+.2. Write a method that takes a list of integers and returns a new list containing the elements larger than 100.
+.3. Write a method that takes a list of integers and returns a new list containing **even** elements **larger** than 100.
+.4. Write a method that takes a list of strings and returns a new list of strings which start with letter ''B'' only.
+.5. (!) Write the signature of a generic ''filter'' function over lists.
+.6. (!!) Implement ''filter''.
+===== 3. Reducing lists =====
+.1. Write a method that takes a list of integers and returns the sum of all the elements.
+.2. Write a method that takes a list of integers and returns the product of all the elements.
+.3. Write a method that takes a list of integers and returns a string representation of all elements separated by commas, e.g. “1,2,3,4”
+.4. Write a method that takes a list of integers and returns their greatest common denominator.
+.5. (Discussion) What is (could be!) common among all implementations? How should a ''fold'' function **signature** (which generalises over all previous ones) look like?
+.6. (!) Implement ''fold'' with all its prerequisites and use it to solve 3.4.
+===== 4. Zipping lists =====
+.1. Write a method that takes two lists and returns a new list of all pairwise products. E.g. ''[2, 4, 2''] and ''[6, 7, 8]'' should yield ''[12, 28, 16]''
+.2. Write a method that takes two lists and returns a new list of all pairwise sums. E.g. ''[2, 4, 2]'' and ''[6, 7, 8]'' should yield ''[8, 11, 10]''
+.3. Write a method that takes a list and returns a new list with the square of each element.
+.4. (!) Identify a generic function which can replace all the above, and implement it. Solve 4.3. using it.