LilyPond scheme predicates

These predicates are only available within LilyPond and defined in Scheme.

Type predicate	Description
alist?	association list (list of pairs)
boolean-or-symbol?	boolean or symbol
cheap-list?	list (use this instead of list? for faster processing)
color?	color
exact-rational?	an exact rational number
fraction?	fraction, as pair
grob-list?	list of grobs
index?	non-negative, exact integer
index-or-markup?	index or markup
key?	index or symbol
key-list?	list of indices or symbols
key-list-or-music?	key list or music
key-list-or-symbol?	key list or symbol
ly:skyline-pair?	pair of skylines
markup?	markup
markup-command-list?	markup command list
markup-list?	markup list
moment-pair?	pair of moment objects
musical-length?	non-negative exact rational, fraction (as pair), moment, or +inf.0
musical-length-as-moment?	non-negative moment with no grace part
musical-length-as-number?	non-negative exact rational or +inf.0
non-negative-number?	non-negative number
number-list?	number list
number-or-grob?	number or grob
number-or-pair?	number or pair
number-or-string?	number or string
number-pair?	pair of numbers
number-pair-list?	list of number pairs
positive-fraction?	positive, finite fraction, as pair
positive-musical-length?	positive exact rational, fraction (as pair), moment, or +inf.0
positive-musical-length-as-moment?	positive moment with no grace part
positive-musical-length-as-number?	positive exact rational or +inf.0
positive-number?	positive number
rational-or-procedure?	an exact rational or procedure
rhythmic-location?	rhythmic location
scale?	non-negative rational, fraction, or moment
scheme?	any type
string-or-music?	string or music
string-or-pair?	string or pair
string-or-symbol?	string or symbol
symbol-key-alist?	alist, with symbols as keys
symbol-list?	symbol list
symbol-list-or-music?	symbol list or music
symbol-list-or-symbol?	symbol list or symbol
void?	void