prefixp

Arguments: prefix sequence

This function returns non-nil value if sequence starts with prefix. prefix and sequence can each be any sequence.

The value returned when sequence does start with prefix is the index into sequence just after prefix.

Examples

(prefixp "foo" "foobar") => 3
(prefixp "foo" "foo") => 3
(prefixp "foo1" "foo2") => nil
(prefixp '(1 2 3) '(1 2 3 4 5 6 7)) => 3
(prefixp (list #\f) "foo")  => 1
(prefixp "f" (vector \#f #\o)) => 1

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Created 2019.8.20.