The $check_syntax() method of a CmdStanModel object checks the Stan program for syntax errors and returns TRUE (invisibly) if parsing succeeds. If invalid syntax in found an error is thrown.

  pedantic = FALSE,
  include_paths = NULL,
  stanc_options = list(),
  quiet = FALSE



(logical) Should pedantic mode be turned on? The default is FALSE. Pedantic mode attempts to warn you about potential issues in your Stan program beyond syntax errors. For details see the Pedantic mode chapter in the Stan Reference Manual.


(character vector) Paths to directories where Stan should look for files specified in #include directives in the Stan program.


(list) Any other Stan-to-C++ transpiler options to be used when compiling the model. See the documentation for the $compile() method for details.


(logical) Should informational messages be suppressed? The default is FALSE, which will print a message if the Stan program is valid or the compiler error message if there are syntax errors. If TRUE, only the error message will be printed.


The $check_syntax() method returns TRUE (invisibly) if the model is valid.

See also

The CmdStanR website ( for online documentation and tutorials.

The Stan and CmdStan documentation:

Other CmdStanModel methods: model-method-compile, model-method-generate-quantities, model-method-optimize, model-method-sample_mpi, model-method-sample, model-method-variational


# \dontrun{ file <- write_stan_file(" data { int N; int y[N]; } parameters { // should have <lower=0> but omitting to demonstrate pedantic mode real lambda; } model { y ~ poisson(lambda); } ") mod <- cmdstan_model(file, compile = FALSE) # the program is syntactically correct, however... mod$check_syntax()
#> Stan program is syntactically correct
# pedantic mode will warn that lambda should be constrained to be positive # and that lambda has no prior distribution mod$check_syntax(pedantic = TRUE)
#> Warning:
#> The parameter lambda has no priors.
#> Warning at '/var/folders/h6/14xy_35x4wd2tz542dn0qhtc0000gn/T/RtmpGraDrG/file2ed27f29a77b.stan', line 11, column 14 to column 20:
#> A poisson distribution is given parameter lambda as a rate parameter
#> (argument 1), but lambda was not constrained to be strictly positive.
#> Stan program is syntactically correct
# }