Thinking in Erlang - A Guide to Functional Programming in Erlang [Jan 2007 Robert Baruch].pdf

Thinking in Erlang
A GUIDE TO FUNCTIONAL PROGRAMMING IN ERLANG FOR THE
EXPERIENCED PROCEDURAL DEVELOPER
Robert Baruch
autophile@
Version
January 31, 2007
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Copyright
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Contents
1 Introduction 4
What this document is not . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
What this document is . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Porting code to Erlang . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Hello, World . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
and running . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Scope of variables 7
No global state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Dealing with no global state . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3 Matching 9
Basic matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Function argument matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
If and case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Guards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 Loops 14
Recursion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Less painful loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5 Processes 18
Doing two things at once . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
munication . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Process termination rea