Chapter 5. Communicating with Humans

Erlang’s origins in telecom switching have left it with a fairly minimal set of tools for communicating with people, but there’s enough there to do worthwhile things. You’ve already used some of it (io:format/1-2) but there are more pieces you’ll want to learn to handle communications with people and sometimes with other applications. At the very least, this chapter will let you build more convenient interfaces for testing your code than calling functions from the Erlang shell.


If you’re feeling completely excited about the recursion you learned in Chapter 4, you may want to jump ahead to Chapter 6, where that recursion will once again be front and center.


Atoms are great for sending messages within a program, even messages that the programmer can remember, but they’re not really designed for communicating outside of the context of Erlang processes. If you need to be assembling sentences or even presenting information, you’ll want something more flexible. Strings, sequences of characters, are the structure you need. You’ve already used strings a little bit, as the double-quoted arguments to io:format in Chapter 4:

io:format("Look out below!~n") ;

The double-quoted content (Look out below!~n) is a string. A string is a sequence of characters. If you want to include a double-quote within the string, you can escape it with a backslash, like \". To include a backslash, you have to use \\, and Appendix A includes a complete list of escapes ...

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