Frontend.Typecheckera type/semantic checker for Stan ASTs
Functions which begin with "check_" return a typed version of their input Functions which begin with "verify_" return unit if a check succeeds, or else throw an Frontend.Errors.SemanticError exception. Other functions which begin with "infer"/"calculate" vary. Usually they return a value, but a few do have error conditions.
All Error.SemanticError excepetions are caught by check_program which turns the ast or exception into a Result.t for external usage
A type environment Frontend.Environment.t is used to hold variables and functions, including Stan math functions. This is a functional map, meaning it is handled immutably.
val check_program :
?allow_undefined_functions:bool ->
Ast.untyped_program ->
(Ast.typed_program * Warnings.t list, Semantic_error.t) Stdlib.resultType check a Stan program, returning a typed program and warnings or an error. When allow_undefined_functions is set to true, the typechecker will not check that all functions have a definition.
val operator_stan_math_return_type :
Middle.Operator.t ->
Middle.UnsizedType.argumentlist ->
(Middle.UnsizedType.returntype * Promotion.t list) optionval stan_math_return_type :
string ->
Middle.UnsizedType.argumentlist ->
Middle.UnsizedType.returntype option