Search­Cowan

This is a small WG2 proposal for Scheme procedures corresponding to the Common Lisp function 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