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| author | Kaz Kylheku <kaz@kylheku.com> | 2022-02-23 21:34:42 -0800 |
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| committer | Kaz Kylheku <kaz@kylheku.com> | 2022-02-23 21:34:42 -0800 |
| commit | 5a8c20fee69d0b68ee60d33a22f0fa46f724e1e2 (patch) | |
| tree | faff4d16d74b4a9dfa3ef81ac606260b3996a5a8 | |
| parent | 3c588285b3f6417bc3d90a1e041a5c16f5baa06a (diff) | |
| download | txr-5a8c20fee69d0b68ee60d33a22f0fa46f724e1e2.tar.gz txr-5a8c20fee69d0b68ee60d33a22f0fa46f724e1e2.tar.bz2 txr-5a8c20fee69d0b68ee60d33a22f0fa46f724e1e2.zip | |
doc: revisit partition-if
* txr.1: Add introductory paragraph, and fine-tune the rest of
the documentation.
| -rw-r--r-- | txr.1 | 33 |
1 files changed, 26 insertions, 7 deletions
@@ -37173,7 +37173,23 @@ function. .mets (partition-if < function < iterable <> [ count ]) .syne .desc -If +The +.code partition-if +function separates the +.meta iterable +sequence into partitions which are identified by the two-argument +.metn function . +The principal idea is that successive overlapping pairs from +.meta iterable +are passed as arguments to +.metn function , +and whenever +.meta function +yields true, those elements are identified as belonging to separate partitions: +a partitioning division shall take place between them. The detailed semantics +is given below, as a procedure. + +Firstly, if .meta sequence is empty, then .code partition-if @@ -37193,7 +37209,7 @@ of the same kind as The partitioning begins with the first element of .meta iterable -being placed into a partition. +being placed into the first partition. The subsequent partitioning is done according to a Boolean .metn function , @@ -37209,7 +37225,7 @@ is reached, the remainder of the sequence is placed into a single partition. After the first element is placed into a partition, the following -process is repeated until the partition is terminated. +partition-building process is repeated until the partition is terminated. .RS .IP 1. If @@ -37219,7 +37235,8 @@ contains no more elements, then the partition terminates. Otherwise, if the .meta count is present, and has a value of zero, then the next available -element is unconditionally deposited into the current partition. +element is unconditionally deposited into the current partition, +and the process repeats from step 1. .IP 3. Otherwise, .meta function @@ -37246,9 +37263,11 @@ same kind as .meta iterable as if by using the .code make-like -function, and appended to the lazy list of partitions. If a next element is -available, it is place into a new partition, and the above process takes place -from step 1. +function, and incorporated as the next element of the lazy list of partitions. + +If, after a partition is thus produced, a next element is available, it is +placed into a new partition, and the above partition-building process takes +place from step 1. Otherwise, the lazy list terminates. .TP* Examples: |