Whitespace
Whitespace characters
The whitespace characters (and their ASCII code points) are the space (0x20), tab (0x09), carriage return (0x0D), and line feed (0x0A).
Whitespace neutrality
Stan treats all whitespace characters identically. Specifically, there is no significance to indentation, to tabs, to carriage returns or line feeds, or to any vertical alignment of text. Any whitespace character is exchangeable with any other.
Other than for readability, the number of whitespaces is also irrelevant. One or more whitespace characters of any type are treated identically by the parser.
Whitespace location
Zero or more whitespace characters may be placed between symbols in a Stan program. For example, zero or more whitespace characters of any variety may be included before and after a binary operation such as a * b, before a statement-ending semicolon, around parentheses or brackets, before or after commas separating function arguments, etc.
Identifiers and literals may not be separated by whitespace. Thus it is not legal to write the number 10000 as 10 000 or to write the identifier normal_lpdf as normal _ lpdf.