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| author | Kaz Kylheku <kaz@kylheku.com> | 2021-12-04 02:20:06 -0800 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2021-12-04 02:20:06 -0800 |
| commit | 3b13057d50e58625e72ad9f18a86f4193a838099 (patch) | |
| tree | 416f63a94c56c845696ca13cfd85e4c6bb3060ef /txr.1 | |
| parent | 536216aa9932b9ab5627f7defb6608b67709c547 (diff) | |
| download | txr-3b13057d50e58625e72ad9f18a86f4193a838099.tar.gz txr-3b13057d50e58625e72ad9f18a86f4193a838099.tar.bz2 txr-3b13057d50e58625e72ad9f18a86f4193a838099.zip | |
tuples*: new function.
* eval.c (eval_init): Register tuples* intrinsic.
* lib.c (tuples_star_func): New static function.
(tuples_star): New function.
* lib.h (tuples_star): Declared.
* tests/012/seq.tl: New test cases.
* txr.1: Documented.
* stdlib/doc-syms.tl: Updated.
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 66 |
1 files changed, 66 insertions, 0 deletions
@@ -35883,6 +35883,72 @@ are lists, and not lazy lists. (tuples 3 (list 1 2) #\ez) -> ((1 2 #\ez)) .brev +.coNP Function @ tuples* +.synb +.mets (tuples < length < sequence <> [ fill-value ]) +.syne +.desc +The +.code tuples* +function produces a lazy list of overlapping tuples taken from +.metn sequence . +The length of the tuples is given by the +.meta length +argument. + +The +.meta length +argument must be a positive integer. + +Tuples are subsequences of consecutive items from the input +.metn sequence , +beginning with consecutive elements. The first tuple in the returned list +begins with the fist item of +.metn sequence ; +the second tuple begins with the second item, and so forth. + +The output of the function is a list, but the tuples themselves are sequences +of the same kind as +.metn sequence . +If +.meta sequence +is any kind of list, they +are lists, and not lazy lists. + +If +.meta sequence +is shorter than +.meta length +then it contains no tuples of that length. In this case, if no +.meta fill-value +argument is specified, then the empty list is returned. +In this same situation, if +.meta fill-value +is specified, then a one-element list is returned, consisting of +a tuple of the required length, consisting of the elements from +.meta sequence +followed by repetitions of +.metn fill-value , +which must be of a type suitable as an element of the sequence. +The +.meta fill-value +is otherwise ignored. + +.TP* Examples: + +.verb +.brev + (tuples* 1 "abc") -> ("a" "b" "c") + (tuples* 2 "abc") -> ("ab" "bc") + (tuples* 3 "abc") -> ("abc") + (tuples* 4 "abc") -> nil + (tuples* 4 "abc" #\z) -> ("abcz") + (tuples* 6 "abc" #\z) -> ("abczzz") + (tuples* 6 "abc" 4) -> error + (tuples* 2 '(a b c)) -> ((a b) (b c)) + (take 3 (tuples* 3 0)) -> ((0 1 2) (1 2 3) (2 3 4)) +.brev + .coNP Function @ partition-by .synb .mets (partition-by < function << sequence ) |