This is not literally the Stan Language definition, which is in the Stan Modeling Language User's Guide and Reference Manual. This repo contains stan-lang.json, which contains various keywords and built-in functions in Stan that I use in maintaining several editor modes and syntax highlighting defintions. In particular, this is used to generate the keyword and function lists in:

• Emacs stan-mode (Current maintainer: @kaz-yos).
• Atom language-stan.
• Pygments StanLexer.
• LaTeX package lstbayes (github).

make all in this directory invokes the create_stan_lang.py Python script. This script parses the following manually maintained files to construct the stan-lang.json file. make clean will delete this file.

• stan-lang-keywords.yaml
• stan-functions-*.txt

The stan-functions-*.txt file is generated by the extract_function_sigs.py script in the stan docs repo. For example, function signatures for Stan version 2.4.x can be generated as follows after cloning the stan-dev/docs repo.

git clone git@github.com:stan-dev/docs.git
cd docs
python3 extract_function_sigs.py

Copy the resulting file named stan-functions-2_24.txt to this repo.

• Stan Reference Manual, Version 2.24.0
  • 6 Expressions
  • 6.2 Variables
  • 8.1 Overview of Stan’s Program Blocks
  • 11 Language Syntax
  • 13 Deprecated Features

• Update functions to latest and parse new array [] int syntax as replacement for int[] syntax
• Add .^ and %/% operators
• Add support for the complex type

• Explain function signature file generation using the extract_function_sigs.py script

• Add offset and multiplier to keywords.

• Links have been updated
• data only arguments in functions such as ODE functions are handled as special cases in the Python parsing script.

• = now used for assignment. <- is deprecated.
• New target keyword for target += expression
• Variable lp__ is no longer supported
• Indicate log_prob() and target() as special functions
• Ternary operator a ? b : c
• New ODE integrate keywords: integrate_ode, integrate_ode_rk45, integrate_ode_bdf which support 6 or 9 arguments.
• Deprecate functions: log_prob, increment_log_prob, binomial_log, multiply_log
• y ~ foo(a, b) is deprecated in favor of target += foo(y | a, b)
• Distribution postfixes _log, _cdf_log, and _ccdf_log deprecated in favor of _lpdf, _lpmf, _lcdf, _lccdf, _cdf, _ccdf.