seqp: expand definition of sequences.

* lib.c (seqp): Use seq_info to classify the object
as a sequence.

* txr.1: Update description of seqp.

1 files changed, 16 insertions, 1 deletions

diff --git a/txr.1 b/txr.1
index a7df3a1f..7b640f76 100644
--- a/txr.1
+++ b/txr.1
@@ -27715,11 +27715,26 @@ if
 is a sequence, otherwise
 .codn nil .
 
-A sequence is defined as a list, vector or string. The object
+Lists, vectors and strings are sequences. The object
 .code nil
 denotes
 the empty list and so is a sequence.
 
+Objects of type
+.code buf
+and
+.code carray
+are sequences, as are hash tables.
+
+Structures which implement the
+.code length
+or
+.code car
+methods are considered sequences.
+
+No other objects are sequences. However, future revisions of
+the language may specify additional objects that are sequences.
+
 .coNP Functions @ length and @ len
 .synb
 .mets (length << object )