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SearchCowan

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This is a small WG2 proposal for Scheme procedures corresponding to the Common Lisp function [http://www.lispworks.com/documentation/lw50/CLHS/Body/f_search.htm SEARCH].

== Procedures ==

`(vector-contains `''test''` `''vector1''` `''vector2''` ` [ [ [ [ ''start1'' ] ''end1'' ] ''start2'' ] ''end2'' ]`)`

`(vector-contains-right `''test''` `''vector1''` `''vector2''` ` [ [ [ [ ''start1'' ] ''end1'' ] ''start2'' ] ''end2'' ]`)`

Searches ''vector2'' from ''start2'' to ''end2'' for the leftmost (for `vector-contains`) or the rightmost (for `vector-contains-right`) sub-vector whose elements are the same (in the sense of ''test'') as those of ''vector1'' from ''start1'' to ''end1''.  ''Test'' is a predicate of two arguments.  The usual default rules and restrictions apply to the start and end arguments.

Returns an index into ''vector2'' if the search succeeds, or `#f` if it fails.

The order in which the search is made is unspecified; in particular, `vector-rsearch` may search from left to right rather than right to left.  The number of times that ''test'' is invoked is also unspecified.

`(list-contains `''test''` `''list1''` `''list2''` ` [ [ [ [ ''start1'' ] ''end1'' ] ''start2'' ] ''end2'' ]`)`

Analogous to `vector-search`, but applicable to lists.


`(string-contains `''test''` `''string1''` `''string2''` ` [ [ [ [ ''start1'' ] ''end1'' ] ''start2'' ] ''end2'' ]`)`

`(string-contains-right `''test''` `''string1''` `''string2''` ` [ [ [ [ ''start1'' ] ''end1'' ] ''start2'' ] ''end2'' ]`)`

Analogous to `vector-contains` and `vector-contains-right`, but applicable to strings.  `String-contains` is already part of SRFI 13.

== Issues ==

SRFI 13's `string-contains(-ci)` allows only the fixed tests `char=?` and `char-ci=?`.  Here are some reasonable ways to resolve the conflict:

 * Omit the ''test'' argument from these procedures

 * Modify SRFI 13 to accept a mandatory ''test'' argument

 * Modify both SRFI 13 and these procedures to make the ''test'' argument optional

 * Rename these separate procedures using a different root name

time

2012-12-24 09:14:52