Mini Project: Infinite List

CS2030S Mini Project: Infinite List
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Task Content
Infinite List
Topic Coverage
Stream concepts
Lambda functions
Variable capture and closures
Immutability
Problem Description
In the lectures, we have implemented an immutable list that is finite. Now, you are going to implement an infinite
version, which is recursive and makes heavy use of the laziness of lambda expressions. Here are some essential
properties on how our infinite list should behave:
An infinite list needs to be as lazy as possible and only generate the elements from the data source when
necessary
An infinite list pipeline needs to be immutable
When an element is generated, it should not be generated again. We do this by caching a copy of the value the
first time an element is generated. Subsequent probing of the same value will result in the cached copy being
returned. You will see the need for this once we go stateful.
The Task
You are to design an implementation of an InfiniteList<T> that supports the following operations:
Data sources:
public static <T> InfiniteList<T> generate(Supplier<? extends T> s)
public static <T> InfiniteList<T> iterate(T seed, UnaryOperator<T> next)
Terminal operations:
public long count();
public <U> U reduce(U identity, BiFunction<U, ? super T, U> accumulator);
public Object[] toArray();
public void forEach(Consumer<? super T> action);
Stateless intermediate operations:
public InfiniteList<T> filter(Predicate<? super T> predicate);
public <R> InfiniteList<R> map(Function<? super T, ? extends R> mapper);
Stateful intermediate operations:
Search search for...
in NUS Websites
NUS WebMail IVLE LIBRARY MAPS
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public InfiniteList<T> limit(long n);
public InfiniteList<T> takeWhile(Predicate<? super T> predicate);
Since InfiniteList is similar to Java's Stream, you are not allowed to import packages from
java.util.stream.
The InfiniteList interface has also been provided for you with most of the methods commented out. It can be
downloaded here. You can uncomment individual methods as you proceed through the levels. Note that an
uncommented version of this same interface will be used when testing in CodeCrunch.
This task is divided into several levels. Read through all the levels to see how the different levels are related.
Remember to:
always compile your program files first before either using jshell to test your program, or using java to run
your program
run checkstyle on your code
Level 1: Getting Lazy
We will start by developing a building block for our InfiniteList: an abstraction for an object of which the value is
not computed until it is needed. Let's build a standalone generic class Lazy<T> (an extension of the one that was
discussed in lecture) that encapsulates a value of type T, with the following operations and properties:
static <T> Lazy<T> ofNullable(T v) creates a lazy object with a given value (precomputed) v. Note
that the Lazy object can contain a null value.
static <T> Lazy<T> of(Supplier<? extends T> supplier) creates a lazy object with a supplier to
produce a value.
Optional<T> get() returns an Optional of the contained value if it is not null; returns Optional.empty
otherwise. If necessary (i.e. when the value is not already cached), get() triggers the computation of the value
encapsulated in the Lazy instance (invoking the chain of supplier, predicates, and functions).
<R> Lazy<R> map(Function<? super T, ? extends R> mapper) applies the function mapper lazily
(i.e., only when needed) to the content of this calling Lazy instance and returns the new Lazy instance. If, upon
evaluation, the content is null, then a lazy object containing null is returned.
Lazy<T> filter(Predicate<? super T> predicate) applies the given predicate lazily to test the
content of the calling Lazy instance. If the predicate returns true, the content is retained, otherwise, the
content becomes null. If the content is already null, then the calling object is returned.
String toString() returns "Lazy[?]" if the value has not been computed; the string representation of the
value enclosed in Lazy[..] otherwise.
As Lazy is the context that handles null values and caching
You are allowed to use the null value in the Lazy class,
Object properties need not be declared final; however they should still be private.
Implementing Lazy and understanding how Lazy works is going to be very useful in later levels.
jshell> /open Lazy.java
jshell> Lazy.ofNullable(4)
$.. ==> Lazy[4]
jshell> Lazy.ofNullable(4).get()
$.. ==> Optional[4]
jshell> Lazy.ofNullable(4).map(x -> x + 4)
$.. ==> Lazy[?]
jshell> Lazy.ofNullable(4).filter(x -> x > 2)
$.. ==> Lazy[?]
jshell> Lazy.ofNullable(4).map(x -> 1).get()
$.. ==> Optional[1]
jshell> Lazy.ofNullable(4).filter(x -> true).get()
$.. ==> Optional[4]
jshell> Lazy.ofNullable(4).filter(x -> false).get()
$.. ==> Optional.empty
jshell> Lazy.ofNullable(4).map(x -> 1).filter(x -> false).get()
$.. ==> Optional.empty
jshell> Lazy.ofNullable(4).filter(x -> false).map(x -> 1).get()
$.. ==> Optional.empty
jshell> Lazy.ofNullable(4).filter(x -> true).map(x -> 1).get()
$.. ==> Optional[1]
jshell> Lazy.ofNullable(4).filter(x -> false).filter(x -> true).get()
$.. ==> Optional.empty
jshell>
jshell> Lazy.ofNullable(null)
$.. ==> Lazy[null]
jshell> Lazy.ofNullable(null).get()
$.. ==> Optional.empty
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jshell> Lazy.ofNullable(null).map(x -> 1)
$.. ==> Lazy[?]
jshell> Lazy.ofNullable(null).filter(x -> true)
$.. ==> Lazy[?]
jshell> Lazy.ofNullable(null).filter(x -> false)
$.. ==> Lazy[?]
jshell> Lazy.ofNullable(null).map(x -> 1).get()
$.. ==> Optional.empty
jshell> Lazy.ofNullable(null).filter(x -> true).get()
$.. ==> Optional.empty
jshell> Lazy.ofNullable(null).filter(x -> false).get()
$.. ==> Optional.empty
jshell>
jshell> Lazy.of(() -> 4)
$.. ==> Lazy[?]
jshell> Lazy.of(() -> 4).get()
$.. ==> Optional[4]
jshell> Lazy.of(() -> 4).map(x -> 1)
$.. ==> Lazy[?]
jshell> Lazy.of(() -> 4).filter(x -> true)
$.. ==> Lazy[?]
jshell> Lazy.of(() -> 4).map(x -> 1).get()
$.. ==> Optional[1]
jshell> Lazy.of(() -> 4).filter(x -> true).get()
$.. ==> Optional[4]
jshell> Lazy.of(() -> 4).filter(x -> false).get()
$.. ==> Optional.empty
jshell> Lazy<Integer> lazy = Lazy.of(() -> 4)
jshell> lazy
lazy ==> Lazy[?]
jshell> lazy.get()
$.. ==> Optional[4]
jshell> lazy
lazy ==> Lazy[4]
jshell>
jshell> Lazy.of(() -> null)
$.. ==> Lazy[?]
jshell> Lazy.of(() -> null).get()
$.. ==> Optional.empty
jshell> Lazy.of(() -> null).map(x -> 1)
$.. ==> Lazy[?]
jshell> Lazy.of(() -> null).filter(x -> false)
$.. ==> Lazy[?]
jshell> Lazy.of(() -> null).map(x -> 1).get()
$.. ==> Optional.empty
jshell> Lazy.of(() -> null).filter(x -> true).get()
$.. ==> Optional.empty
jshell> Lazy.of(() -> null).filter(x -> false).get()
$.. ==> Optional.empty
jshell> Lazy<Integer> lazy = Lazy.of(() -> null)
jshell> lazy
lazy ==> Lazy[?]
jshell> lazy.get()
$.. ==> Optional.empty
jshell> lazy
lazy ==> Lazy[null]
Compile your program by running the following on the command line:
$ javac -Xlint:rawtypes *.java
Level 2: To Infinity and Beyond
Define the InfiniteListImpl class that implements the InfiniteList interface. Write the static generate and
iterate methods that initiate the initial list pipeline. You are encouraged to adapt the implementation demonstrated in
class using the head and tail suppliers. If you do it right, you need only have these two declared private final and
nothing else. That said, if you feel compelled to introduce other fields to aid in your implementation, feel free to do so.
But note that the implementation demonstrated in class does not support caching of computed values. To solve this lab,
you will need to use the type Lazy<T> for the head to take advantage of its laziness, instead of Supplier<T>.
For debugging purposes, include a method InfiniteList<T> peek() within your implementation that prints the
first element of the infinite list to the standard output and returns the rest of the list as an InfiniteList. This enables
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the chaining of peek() methods to produce an output of a sequence of stream elements. Note that peek() is solely
for the purpose of debugging, until a terminal operation is introduced at a later level.
jshell> InfiniteList<Integer> list
jshell> InfiniteList.generate(() -> 1) instanceof InfiniteListImpl
$.. ==> true
jshell> InfiniteList.iterate(1, x -> x + 1) instanceof InfiniteListImpl
$.. ==> true
jshell> list = InfiniteListImpl.generate(() -> 1).peek()
1
jshell> list = InfiniteListImpl.iterate(1, x -> x + 1).peek()
1
jshell> list = InfiniteListImpl.iterate(1, x -> x + 1).peek().peek()
1
2
jshell> InfiniteList<Integer> list2 = list.peek()
3
jshell> list != list2
$.. ==> true
jshell> InfiniteList<String> list = InfiniteListImpl.iterate("A", x -> x + "Z").peek().pee
A
AZ
AZZ
jshell>
jshell> UnaryOperator<Integer> op = x -> { System.out.printf("iterate: %d -> %d\n", x, x +
jshell> list2 = InfiniteList.iterate(1, op).peek().peek()
1
iterate: 1 -> 2
2
iterate: 2 -> 3
jshell>
jshell> /exit
Compile your program by running the following on the command line:
$ javac -Xlint:rawtypes *.java
$ jshell -q Lazy.java InfiniteList.java InfiniteListImpl.java < level2.jsh
Check your styling by issuing the following
$ checkstyle *.java
Level 3: Map and Filter
Now implement the map and filter operations. In particular, if an element from an upstream operation does not pass
through filter, an Optional.empty() will be generated. peek() does not print anything if the element is
Optional.empty().
jshell> InfiniteList<Integer> list, list2
jshell> list = InfiniteList.generate(() -> 1).map(x -> x * 2)
jshell> list2 = list.peek()
2
jshell> list2 = list.peek()
2
jshell> InfiniteList.generate(() -> 1).map(x -> x * 2) instanceof InfiniteListImpl
$.. ==> true
jshell> list = InfiniteList.generate(() -> 1).map(x -> x * 2).peek()
2
jshell> list = InfiniteList.generate(() -> 1).map(x -> x * 2).peek().peek()
2
2
jshell> list = InfiniteList.iterate(1, x -> x + 1).map(x -> x * 2).peek().peek()
2
4
jshell>
jshell> Supplier<Integer> generator = () -> { System.out.println("generate: 1"); return 1
jshell> Function<Integer,Integer> doubler = x -> { System.out.printf("map: %d -> %d\n", x
jshell> Function<Integer,Integer> oneLess = x -> { System.out.printf("map: %d -> %d\n", x
jshell> list = InfiniteList.generate(generator).map(doubler).peek().peek()
generate: 1
map: 1 -> 2
2
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generate: 1
map: 1 -> 2
2
jshell> list = InfiniteList.generate(generator).map(doubler).map(oneLess).peek().peek()
generate: 1
map: 1 -> 2
map: 2 -> 1
1
generate: 1
map: 1 -> 2
map: 2 -> 1
1
jshell>
jshell> list = InfiniteList.iterate(1, x -> x + 1).filter(x -> x % 2 == 0)
jshell> list2 = list.peek()
jshell> list2 = list.peek()
jshell> InfiniteList.iterate(1, x -> x + 1).filter(x -> x % 2 == 0) instanceof InfiniteLis
$.. ==> true
jshell> list = InfiniteList.iterate(1, x -> x + 1).filter(x -> x % 2 == 0).peek().peek()
2
jshell> list = InfiniteList.iterate(1, x -> x + 1).filter(x -> x % 2 == 0).filter(x -> x <
2
jshell>
jshell> Predicate<Integer> isEven = x -> { System.out.printf("filter: %d -> %b\n", x, x %
jshell> Predicate<Integer> lessThan10 = x -> { System.out.printf("filter: %d -> %b\n", x,
jshell> UnaryOperator<Integer> op = x -> { System.out.printf("iterate: %d -> %d\n", x, x +
jshell> list = InfiniteList.iterate(1, op).filter(isEven).peek().peek()
filter: 1 -> false
iterate: 1 -> 2
filter: 2 -> true
2
iterate: 2 -> 3
jshell> list = InfiniteList.iterate(1, op).filter(isEven).filter(lessThan10).peek().peek(
filter: 1 -> false
iterate: 1 -> 2
filter: 2 -> true
filter: 2 -> true
2
iterate: 2 -> 3
jshell>
jshell> list = InfiniteList.iterate(1, op).map(doubler).filter(isEven).filter(lessThan10)
map: 1 -> 2
filter: 2 -> true
filter: 2 -> true
2
iterate: 1 -> 2
map: 2 -> 4
filter: 4 -> true
filter: 4 -> true
4
iterate: 2 -> 3
jshell> list = InfiniteList.iterate(1, op).filter(isEven).map(doubler).filter(lessThan10)
filter: 1 -> false
iterate: 1 -> 2
filter: 2 -> true
map: 2 -> 4
filter: 4 -> true
4
iterate: 2 -> 3
jshell> list = InfiniteList.iterate(1, op).filter(isEven).filter(lessThan10).map(doubler)
filter: 1 -> false
iterate: 1 -> 2
filter: 2 -> true
filter: 2 -> true
map: 2 -> 4
4
iterate: 2 -> 3
jshell> /exit
Compile your program by running the following on the command line:
$ javac -Xlint:rawtypes *.java
$ jshell -q <your java files> < level3.jsh
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Check your styling by issuing the following
$ checkstyle *.java
Level 4: Emptiness and Limitations
Now, create a subtype of InfiniteList that represents an empty list called EmptyList. The EmptyList should
return true when isEmpty() is called and it should return itself for intermediate operations and appropriate values for
terminal operations.
Then, implement the limit method. There is now a need to differentiate between an Optional.empty() produced
from filter and the end of the stream in limit. Make use of EmptyList to indicate the end of the stream. When
dealing with limit, you will need to decide if the upstream element
produces an empty list;
produces an Optional.empty and ignored by limit; or
produces a stream element and accounted for by limit
The other operation to truncate an infinite list is the takeWhile operator. The same considerations that you have given
to limit would probably apply here.
jshell> InfiniteList.iterate(1, x -> x + 1).isEmpty()
$.. ==> false
jshell> InfiniteList.generate(() -> 2).isEmpty()
$.. ==> false
jshell> InfiniteList.generate(() -> 2).filter(x -> x % 3 == 0).isEmpty()
$.. ==> false
jshell> InfiniteList.iterate(1, x -> x + 1).map(x -> 2).isEmpty()
$.. ==> false
jshell> InfiniteList.iterate(1, x -> x + 1).filter(x -> x % 2 == 0).isEmpty()
$.. ==> false
jshell> new EmptyList<>().isEmpty()
$.. ==> true
jshell> new EmptyList<>().map(x -> 2).isEmpty()
$.. ==> true
jshell> new EmptyList<>().filter(x -> true).isEmpty()
$.. ==> true
jshell> new EmptyList<>().filter(x -> false).isEmpty()
$.. ==> true
jshell>
jshell> InfiniteList.iterate(1, x -> x + 1).limit(0).isEmpty()
$.. ==> true
jshell> InfiniteList.iterate(1, x -> x + 1).limit(1).isEmpty()
$.. ==> false
jshell> InfiniteList.iterate(1, x -> x + 1).limit(-1).isEmpty()
$.. ==> true
jshell>
jshell> UnaryOperator<Integer> op = x -> { System.out.printf("iterate: %d -> %d\n", x, x +
jshell> InfiniteList.iterate(1, op).limit(0).isEmpty()
$.. ==> true
jshell> InfiniteList.iterate(1, op).limit(1).isEmpty()
$.. ==> false
jshell> InfiniteList.iterate(1, op).limit(2).isEmpty()
$.. ==> false
jshell> InfiniteList<Integer> list;
jshell> list = InfiniteList.iterate(1, op).limit(0).peek()
jshell> list = InfiniteList.iterate(1, op).limit(1).peek()
1
jshell> list = InfiniteList.iterate(1, op).limit(1).peek().peek()
1
jshell> list = InfiniteList.iterate(1, op).limit(2).peek().peek().peek()
1
iterate: 1 -> 2
2
jshell> list = InfiniteList.iterate(1, op).limit(2).limit(1).peek().peek()
1
jshell> list = InfiniteList.iterate(1, op).limit(1).limit(2).peek().peek()
1
jshell>
jshell> InfiniteList.iterate(1, op).takeWhile(x -> x < 0).isEmpty()
$.. ==> false
jshell> InfiniteList.iterate(1, op).takeWhile(x -> x < 2).isEmpty()
$.. ==> false
jshell> list = InfiniteList.iterate(1, op).takeWhile(x -> x < 0).peek()
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jshell> list = InfiniteList.iterate(1, op).takeWhile(x -> x < 2).peek().peek()
1
iterate: 1 -> 2
jshell> list = InfiniteList.iterate(1, op).takeWhile(x -> x < 2).takeWhile(x -> x < 0).pee
jshell> list = InfiniteList.iterate(1, op).takeWhile(x -> x < 0).takeWhile(x -> x < 2).pee
jshell> list = InfiniteList.iterate(1, op).takeWhile(x -> x < 5).takeWhile(x -> x < 2).pee
1
iterate: 1 -> 2
jshell>
jshell> Predicate<Integer> lessThan5 = x -> { System.out.printf("takeWhile: %d -> %b\n", x
jshell> list = InfiniteList.iterate(1, op).takeWhile(lessThan5).peek().peek()
takeWhile: 1 -> true
1
iterate: 1 -> 2
takeWhile: 2 -> true
2
iterate: 2 -> 3
jshell>
jshell> /exit
Compile your program by running the following on the command line:
$ javac -Xlint:rawtypes *.java
$ jshell -q Lazy.java InfiniteList.java InfiniteListImpl.java < level4.jsh
Check your styling by issuing the following
$ checkstyle *.java
Level 5: Terminals
Now, we are going to implement the terminal operations: forEach, count, reduce, and toArray.
jshell> new EmptyList<>().toArray()
$.. ==> Object[0] { }
jshell> InfiniteList.iterate(0, i -> i + 1).limit(10).limit(3).toArray()
$.. ==> Object[3] { 0, 1, 2 }
jshell> InfiniteList.iterate(0, i -> i + 1).limit(3).limit(100).toArray()
$.. ==> Object[3] { 0, 1, 2 }
jshell> InfiniteList.generate(() -> 1).limit(0).toArray()
$.. ==> Object[0] { }
jshell> InfiniteList.generate(() -> 1).limit(2).toArray()
$.. ==> Object[2] { 1, 1 }
jshell> Random rnd = new Random(1)
jshell> InfiniteList.generate(() -> rnd.nextInt() % 100).limit(4).toArray();
$.. ==> Object[4] { -25, 76, 95, 26 }
jshell> InfiniteList.generate(() -> "A").map(x -> x + "-").map(str -> str.length()).limit
$.. ==> Object[4] { 2, 2, 2, 2 }
jshell> InfiniteList.generate(() -> "A").limit(4).map(x -> x + "-").map(str -> str.length
$.. ==> Object[4] { 2, 2, 2, 2 }
jshell> InfiniteList.generate(() -> "A").map(x -> x + "-").limit(4).map(str -> str.length
$.. ==> Object[4] { 2, 2, 2, 2 }
jshell> InfiniteList.iterate(1, x -> x + 1).limit(4).filter(x -> x % 2 == 0).toArray()
$.. ==> Object[2] { 2, 4 }
jshell> InfiniteList.iterate(1, x -> x + 1).filter(x -> x % 2 == 0).limit(4).toArray()
$.. ==> Object[4] { 2, 4, 6, 8 }
jshell> InfiniteList.iterate(0, x -> x + 1).filter(x -> x > 10).filter(x -> x < 20).limit
$.. ==> Object[5] { 11, 12, 13, 14, 15 }
jshell> InfiniteList.iterate(0, x -> x + 1).filter(x -> x > 10).map(x -> x.hashCode() % 30
$.. ==> Object[5] { 11, 12, 13, 14, 15 }
jshell> InfiniteList.iterate(0, x -> x + 1).takeWhile(x -> x < 3).toArray()
$.. ==> Object[3] { 0, 1, 2 }
jshell> InfiniteList.iterate(0, x -> x + 1).takeWhile(x -> x < 0).toArray()
$.. ==> Object[0] { }
jshell> InfiniteList.iterate(0, x -> x + 1).takeWhile(x -> x < 10).takeWhile(x -> x < 5).t
$.. ==> Object[5] { 0, 1, 2, 3, 4 }
jshell> InfiniteList.iterate(0, x -> x + 1).map(x -> x).takeWhile(x -> x < 4).limit(1).toA
$.. ==> Object[1] { 0 }
jshell> InfiniteList.iterate(0, x -> x + 1).limit(4).takeWhile(x -> x < 2).toArray()
$.. ==> Object[2] { 0, 1 }
jshell> InfiniteList.iterate(0, x -> x + 1).map(x -> x * x).filter(x -> x > 10).limit(1).t
$.. ==> Object[1] { 16 }
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jshell> InfiniteList.iterate(0, x -> x + 1).filter(x -> x > 10).map(x -> x * x).limit(1).t
$.. ==> Object[1] { 121 }
jshell> Random rnd = new Random(1)
jshell> InfiniteList.generate(() -> rnd.nextInt() % 100).filter(x -> x > 10).limit(4).toAr
$.. ==> Object[4] { 76, 95, 26, 69 }
jshell>
jshell> new EmptyList<>().count()
$.. ==> 0
jshell> InfiniteList.iterate(0, x -> x + 1).limit(0).count()
$.. ==> 0
jshell> InfiniteList.iterate(0, x -> x + 1).limit(1).count()
$.. ==> 1
jshell> InfiniteList.iterate(0, x -> x + 1).filter(x -> x % 2 == 1).limit(10).count()
$.. ==> 10
jshell> InfiniteList.iterate(0, x -> x + 1).limit(10).filter(x -> x % 2 == 1).count()
$.. ==> 5
jshell> InfiniteList.iterate(0, x -> x + 1).takeWhile(x -> x < 10).count()
$.. ==> 10
jshell> InfiniteList.iterate(0, x -> x + 1).takeWhile(x -> x < 10).filter(x -> x % 2 == 0
$.. ==> 5
jshell> Random rnd = new Random(1)
jshell> InfiniteList.generate(() -> Math.abs(rnd.nextInt()) % 100).takeWhile(x -> x > 5).c
$.. ==> 9
jshell>
jshell> new EmptyList<Integer>().reduce(100, (x,y) -> x*y)
$.. ==> 100
jshell> InfiniteList.iterate(0, x -> x + 1).limit(5).reduce(0, (x, y) -> x + y)
$.. ==> 10
jshell> InfiniteList.iterate(0, x -> x + 1).limit(0).reduce(0, (x, y) -> x + y)
$.. ==> 0
jshell> InfiniteList.iterate(0, x -> x + 1).map(x -> x * x).limit(5).reduce(1, (x, y) -> x
$.. ==> 0
jshell> Random rnd = new Random(1)
jshell> InfiniteList.generate(() -> rnd.nextInt() % 100).filter(x -> x > 0).limit(10).redu
$.. ==> 95
jshell>
jshell> UnaryOperator<Integer> op = x -> { System.out.printf("iterate: %d -> %d\n", x, x +
jshell> Supplier<Integer> generator = () -> { System.out.println("generate: 1"); return 1
jshell> Function<Integer,Integer> doubler = x -> { System.out.printf("map: %d -> %d\n", x
jshell> Function<Integer,Integer> oneLess = x -> { System.out.printf("map: %d -> %d\n", x
jshell> Predicate<Integer> lessThan100 = x -> { System.out.printf("takeWhile: %d -> %b\n"
jshell> Predicate<Integer> moreThan10 = x -> { System.out.printf("filter: %d -> %b\n", x,
jshell>
jshell> InfiniteList.iterate(0, op).filter(lessThan100).map(doubler).takeWhile(lessThan100
takeWhile: 0 -> true
map: 0 -> 0
takeWhile: 0 -> true
map: 0 -> -1
iterate: 0 -> 1
takeWhile: 1 -> true
map: 1 -> 2
takeWhile: 2 -> true
map: 2 -> 1
iterate: 1 -> 2
takeWhile: 2 -> true
map: 2 -> 4
takeWhile: 4 -> true
map: 4 -> 3
iterate: 2 -> 3
takeWhile: 3 -> true
map: 3 -> 6
takeWhile: 6 -> true
map: 6 -> 5
iterate: 3 -> 4
takeWhile: 4 -> true
map: 4 -> 8
takeWhile: 8 -> true
map: 8 -> 7
$.. ==> Object[5] { -1, 1, 3, 5, 7 }
jshell> InfiniteList.generate(generator).filter(lessThan100).map(doubler).takeWhile(lessTh
generate: 1
takeWhile: 1 -> true
map: 1 -> 2
takeWhile: 2 -> true
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map: 2 -> 1
generate: 1
takeWhile: 1 -> true
map: 1 -> 2
takeWhile: 2 -> true
map: 2 -> 1
generate: 1
takeWhile: 1 -> true
map: 1 -> 2
takeWhile: 2 -> true
map: 2 -> 1
generate: 1
takeWhile: 1 -> true
map: 1 -> 2
takeWhile: 2 -> true
map: 2 -> 1
generate: 1
takeWhile: 1 -> true
map: 1 -> 2
takeWhile: 2 -> true
map: 2 -> 1
$.. ==> Object[5] { 1, 1, 1, 1, 1 }
jshell>
jshell> new EmptyList<>().forEach(System.out::println)
jshell> InfiniteList.iterate(0, x -> x + 1).limit(0).forEach(System.out::println)
jshell> InfiniteList.iterate(0, x -> x + 1).limit(1).forEach(System.out::println)
0
jshell> InfiniteList.iterate(0, x -> x + 1).filter(x -> x % 2 == 1).limit(10).forEach(Syst
1
3
5
7
9
11
13
15
17
19
jshell> InfiniteList.iterate(0, x -> x + 1).limit(10).filter(x -> x % 2 == 1).forEach(Syst
1
3
5
7
9
jshell> InfiniteList.iterate(0, x -> x + 1).takeWhile(x -> x < 10).forEach(System.out::pri
0
1
2
3
4
5
6
7
8
9
jshell> InfiniteList.iterate(0, x -> x + 1).takeWhile(x -> x < 10).filter(x -> x % 2 == 0
0
2
4
6
8
jshell> /exit
Compile your program by running the following on the command line:
$ javac -Xlint:rawtypes *.java
You should try to test your implementation as exhaustively as you can before submitting to CodeCrunch. We shall be
using another client class to test your implementation.
26/11/2021, 03:21 CodeCrunch
https://codecrunch.comp.nus.edu.sg/task_view.php?tid=5103 10/10
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