Errata

Lazy paging and concatenation

I have two suggestion with this:

1. capitalize: it's 2nd-level title, so
Lazy paging and concatenation -> Lazy Pagination and Concatenation

2. 'pagination', rather than 'paging'
In my opinion, 'pagination' is more suitable word in this case.
'paging' typically related to "memory management".

Original code:

interface Subscriber<T> implements Observer<T>, Subscription {
...
}

Subscriber is an abstract class, not an interface.

IN: the mechanics of two asynchronous Observables...

plural 's' maybe not to be FIXED WIDTH FONT FORMAT

IN: Lazyiness allows composing Observables together without data loss...

There are two:

1. in fixed width "Observables", plural 's' maybe not to be FIXED WIDTH FONT FORMAT

2. Lazyiness -> Laziness

In other words, the Rx Observable allows programming with async data via push just like Streams around Iterables and Lists using synchronous pull.

(fixed width) Iterables -> (fixed) Iterable (normal) s
(fixed width) Lists -> (fixed) List (normal) s

Design Patterns: Elements of Reusable Object-Oriented So ware by Erich Gamma and Richard Helm [Addison-Wesley])

"." is missing in the end of sentence.

For example, the first filter() does not remove 9 from Observable.just(8, 9, 10)

"." is missing in the end of the sentence.

Following the UNIX philosophy of "small, sharp tools,”

closing double quote and comma position:
"small, sharp tools,” -> "small, sharp tools”,

alphabet
.compose(odd())
.forEach(System.out::println);

should be

alphabet
.compose(ClassName::odd)
.forEach(System.out::println);

where ClassName is the name of the class. Compose needs a method reference here.

(notice how reduce() is implemented using scan().take Last(1).single():

Maybe closing pharenthesis is missing:
...Last(1).single(): -> ...Last(1).single()):

We build an infinite stream of numbers (1, 2, 3, 4, 1, 2, 3...), apply our operator ("1", "3", "1", "3"...)

missing commas:

-> (1, 2, 3, 4, 1, 2, 3,...), apply our operator ("1", "3", "1", "3",...)

For example in Tomcat there are 200 threads by default in the executors that are responsible for handling requests.

maybe missing comma:

For example in Tomcat -> For example, in Tomcat

resulting in OutOfMemor yError for cases in which there are a of large number of outstanding tasks.

there are a of large number of -> there are a large number of