Psalm Requires PHP >= 7.1 and Composer.

composer require --dev vimeo/psalm

Add a psalm.xml config:

./vendor/bin/psalm --init [source_directory=src] [config_level=3]

where config_level represents how strict you want Psalm to be. 1 is the strictest, 8 is the most lenient.


$ ./vendor/bin/psalm --init src 3
Config file created successfully. Please re-run psalm.

Then run Psalm:


Psalm will probably find a number of issues - find out how to deal with them in Dealing with code issues.