R5RS primary predicates

Primary predicates can be applied to any expression. They can be used on their own as predicates for LilyPond functions. The predicates here are part of the Scheme standard R5RS.

Type predicate	Description
boolean?	boolean
char?	character
complex?	complex number
eof-object?	end-of-file object
input-port?	input port
integer?	integer
list?	list (use cheap-list? for faster processing)
null?	null
number?	number
output-port?	output port
pair?	pair
port?	port
procedure?	procedure
rational?	rational number
real?	real number
string?	string
symbol?	symbol
vector?	vector