Here are a few words about the presentation of materials.
Some textbooks on programming invite their readers on the very first pages to print "Hello, world!" using a simple program. Their authors think that as soon as their readers start learning programming,
they should refer to program texts and gradually get used to how the programs may look,
which will later facilitate their learning. However,
the result is that the reader has to deal with several unknown terms at the same time and has to just guess the content and properties of some lines in the program.
This may result in misconceptions and vacancies in the reader's knowledge.