title	author	date	output
Stan Linter	Breck Baldwin	4/20/2020	html_document

Stan Linter

This is a heuristic linter for .stan programs that attemtps to enforce the stan program style guide from the Stan User's Guide.

Using the linter

You must have python 3 installed and be comfortable with the command line.

1. Open a terminal and cd to the location of your .stan file. There is an example program in the distubution that we will use.
2. cd <path to stan_linter>
3. python stan_linter.py small.stan
4. Output should be:

linting small.stan

spaces needed around operator =:line number:10=' real<lower=0> sigma;'

missing space after char 19',':line number:14=' alpha ~ normal(5,10);'

Modifying the linter

I created the linter to help clean up .stan models in the user's guide and have just gotten started. The linter is line based and I have assumed that the .stan programs pass the Stan compiler. The linter is mostly a series of regular expressions that look for common problems and report back.

A good way to add patterns is to add the desired output to the unit test file stan_linter_test.py and then add a subroutine to stan_linter.py to pass the test. The test program is run using pytest and the complete command to run is pytest stan_linter_test.py.