`(gc ['cnt [cnt2]]) -> cnt | NIL`

- Forces a garbage collection. When
`cnt`

is given, so many megabytes of free cells are reserved, increasing the heap size if necessary. If`cnt`

is zero, all currently unused heap blocks are purged, decreasing the heap size if possible. If`cnt2`

(64-bit version only) is given, the reserve size (defaults to 1 megabyte) is set to that value. Before collection (but after argument evaluation) the global variables`@`

and`@@`

are set to`NIL`

. See also`heap`

.`: (gc) -> NIL : (heap) -> 2 : (gc 4) -> 4 : (heap) -> 5`

`(ge0 'any) -> num | NIL`

- Returns
`num`

when the argument is a number and greater or equal zero, otherwise`NIL`

. See also`lt0`

,`le0`

,`gt0`

,`=0`

and`n0`

.`: (ge0 -2) -> NIL : (ge0 3) -> 3 : (ge0 0) -> 0`

`(genKey 'var 'cls ['hook ['num1 ['num2]]]) -> num`

- Generates a key for a database tree. If a minimal key
`num1`

and/or a maximal key`num2`

is given, the next free number in that range is returned. Otherwise, the current maximal key plus one is returned. See also`useKey`

,`genStrKey`

and`maxKey`

.`: (maxKey (tree 'nr '+Item)) -> 8 : (genKey 'nr '+Item) -> 9`

`(genStrKey 'sym 'var 'cls ['hook]) -> sym`

- Generates a unique string for a database tree, by prepending as many "# "
sequences as necessary. See also
`genKey`

.`: (genStrKey "ben" 'nm '+User) -> "# ben"`

`(get 'sym1|lst ['sym2|cnt ..]) -> any`

- Fetches a value
`any`

from the properties of a symbol, or from a list. From the first argument`sym1|lst`

, values are retrieved in successive steps by either extracting the value (if the next argument is zero) or a property from a symbol, the`asoq`

ed element (if the next argument is a symbol), the n'th element (if the next argument is a positive number) or the n'th CDR (if the next argument is a negative number) from a list. See also`put`

,`;`

and`:`

.`: (put 'X 'a 1) -> 1 : (get 'X 'a) -> 1 : (put 'Y 'link 'X) -> X : (get 'Y 'link) -> X : (get 'Y 'link 'a) -> 1 : (get '((a (b . 1) (c . 2)) (d (e . 3) (f . 4))) 'a 'b) -> 1 : (get '((a (b . 1) (c . 2)) (d (e . 3) (f . 4))) 'd 'f) -> 4 : (get '(X Y Z) 2) -> Y : (get '(X Y Z) 2 'link 'a) -> 1`

`(getd 'any) -> fun | NIL`

- Returns
`fun`

if`any`

is a symbol that has a function definition, otherwise`NIL`

. See also`fun?`

.`: (getd '+) -> 67327232 : (getd 'script) -> ((File . @) (load File)) : (getd 1) -> NIL`

`(getl 'sym1|lst1 ['sym2|cnt ..]) -> lst`

- Fetches the complete property list
`lst`

from a symbol. That symbol is`sym1`

(if no other arguments are given), or a symbol found by applying the`get`

algorithm to`sym1|lst1`

and the following arguments. See also`putl`

and`maps`

.`: (put 'X 'a 1) -> 1 : (put 'X 'b 2) -> 2 : (put 'X 'flg T) -> T : (getl 'X) -> (flg (2 . b) (1 . a))`

`(glue 'any 'lst) -> sym`

- Builds a new transient symbol (string) by
`pack`

ing the`any`

argument between the individual elements of`lst`

. See also`text`

.`: (glue "," '(a b c d)) -> "a,b,c,d"`

`(goal '([pat 'any ..] . lst) ['sym 'any ..]) -> lst`

- Constructs a Pilog query list from the list of
clauses
`lst`

. The head of the argument list may consist of a sequence of pattern symbols (Pilog variables) and expressions, which are used together with the optional`sym`

and`any`

arguments to form an initial environment. See also`prove`

and`fail`

.`: (goal '((likes John @X))) -> (((1 (0) NIL ((likes John @X)) NIL T))) : (goal '(@X 'John (likes @X @Y))) -> (((1 (0) NIL ((likes @X @Y)) NIL ((0 . @X) 1 . John) T)))`

`(group 'lst) -> lst`

- Builds a list of lists, by grouping all elements of
`lst`

with the same CAR into a common sublist. See also Comparing,`by`

,`sort`

and`uniq`

.`: (group '((1 . a) (1 . b) (1 . c) (2 . d) (2 . e) (2 . f))) -> ((1 a b c) (2 d e f)) : (by name group '("x" "x" "y" "z" "x" "z"))) -> (("x" "x" "x") ("y") ("z" "z")) : (by length group '(123 (1 2) "abcd" "xyz" (1 2 3 4) "XY")) -> ((123 "xyz") ((1 2) "XY") ("abcd" (1 2 3 4))`

`(gt0 'any) -> num | NIL`

- Returns
`num`

when the argument is a number and greater than zero, otherwise`NIL`

. See also`lt0`

,`le0`

,`ge0`

,`=0`

and`n0`

.`: (gt0 -2) -> NIL : (gt0 3) -> 3`