dtonhofer
Functional Programming in Java, Second Edition: Chapter 3: Add an example of a filter negation
The filter stream operation appears on several places in Chapter 2 and Chapter 3, so it’s difficult to say where to put this, but there should be an example of “filtering by a negated predicate”, maybe on page 60:
The code presented:
Files.list(Paths.get("."))
.filter(Files::isDirectory)
.forEach(System.out::println);
But what if we want to have everything EXCEPT directories while using the method reference?
This would of course work:
Files.list(Paths.get("."))
.filter(file -> !Files.isDirectory(file))
.forEach(System.out::println);
But nicer is this application of “predicate composition”
Files.list(Paths.get("."))
.filter(Predicate.not(file -> Files.isDirectory(file)))
.forEach(System.out::println);
which simplifies to
Files.list(Paths.get("."))
.filter(Predicate.not(Files::isDirectory))
.forEach(System.out::println);
Popular Pragmatic Bookshelf topics
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks”
While running the smoke tests in Chapter 2, I get these...
New
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
New
@noelrappin
Running the webpack dev server, I receive the following warning:
ERROR in tsconfig.json
TS18003: No inputs were found in c...
New
I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...
New
When running tox for the first time, I got the following error:
ERROR: InterpreterNotFound: python3.10
I realised that I was running ...
New
Hi,
I completed chapter 6 but am getting the following error when running:
thread 'main' panicked at 'Failed to load texture: IoError(O...
New
Hi all,
currently I wonder how the Tailwind colours work (or don’t work).
For example, in app/views/layouts/application.html.erb I have...
New
Modern front-end development for Rails, second edition - Struggling to get the first chapter to work
After running /bin/setup, the first error was: The foreman' command exists in these Ruby versions: That was easy to fix: gem install fore...
New
Docker-Machine became part of the Docker Toolbox, which was deprecated in 2020, long after Docker Desktop supported Docker Engine nativel...
New
I just bought this book to learn about Android development, and I’m already running into a major issue in Ch. 1, p. 20: “Update activity...
New
Other popular topics
Algorithms and data structures are much more than abstract concepts. Mastering them enables you to write code that runs faster and more e...
New
Learn from the award-winning programming series that inspired the Elixir language, and go on a step-by-step journey through the most impo...
New
New
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
New
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
A few weeks ago I started using Warp a terminal written in rust. Though in it’s current state of development there are a few caveats (tab...
New
We’ve talked about his book briefly here but it is quickly becoming obsolete - so he’s decided to create a series of 7 podcasts, the firs...
New
Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New
Author Spotlight
Erin Dees
@undees
Welcome to our new author spotlight! We had the pleasure of chatting with Erin Dees, co-author of ...
New
If you’re getting errors like this:
psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /java
- /emacs
- /haskell
- /svelte
- /onivim
- /typescript
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /flutter
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /deepseek
- /centos
- /php
- /scala
- /react-native
- /lisp
- /textmate
- /sublime-text
- /nixos
- /debian
- /agda
- /django
- /deno
- /kubuntu
- /arch-linux
- /nodejs
- /spring
- /ubuntu
- /revery
- /manjaro
- /julia
- /lua
- /diversity
- /markdown
- /c









