Java: imperative + object-oriented
Michael Feather:
“In OPP we encapsulate the moving parts; in FP we eliminate the moving parts.”
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List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
//double of even numbers
List<Integer> doubled = new ArrayList<>();
for (int i = 0; i < numbers.size(); i++) {
if (numbers.get(i) % 2 == 0) {
doubled.add(numbers.get(i) * 2);
}
}
System.out.println(doubled);
System.out.println(
numbers.stream()
.filter( e -> e % 2 == 0)
.map( e -> e * 2)
.collect(toList()));
functional programming == functional composition + lazy evaluation
Collection Pipeline Pattern
Stream is not a data structure it is an abstraction of functions
bucket vs pipeline
List/Set Stream
dataflow computing
Serverless
