last function becomes generic.

* lib.c (last): Handle non-list sequences via sub function.

* txr.1: Updated description of last.

2 files changed, 17 insertions, 6 deletions

diff --git a/lib.c b/lib.c
index 0dc1b543..d658f356 100644
--- a/lib.c
+++ b/lib.c
@@ -559,10 +559,13 @@ loc lastcons(val list)
   return ret;
 }
 
-val last(val list)
+val last(val seq)
 {
-  loc p = lastcons(list);
-  return nullocp(p) ? list : deref(p);
+  if (listp(seq)) {
+    loc p = lastcons(seq);
+    return nullocp(p) ? seq : deref(p);
+  }
+  return sub(seq, negone, t);
 }
 
 val nthcdr(val pos, val list)
diff --git a/txr.1 b/txr.1
index 045d760e..4bb31634 100644
--- a/txr.1
+++ b/txr.1
@@ -14850,11 +14850,11 @@ See the relevant examples below.
 
 .coNP Function @ last
 .synb
-.mets (last << list )
+.mets (last << seq )
 .syne
 .desc
 If
-.meta list
+.meta seq
 is a nonempty proper or improper list, the
 .code last
 function
@@ -14863,13 +14863,21 @@ returns the last cons cell in the list: that cons cell whose
 field is a terminating atom.
 
 If
-.meta list
+.meta seq
 is
 .codn nil ,
 then
 .code nil
 is returned.
 
+If
+.meta seq
+is a non-list sequence, then a one-element suffix of
+.code seq
+is returned, or an empty suffix if
+.code seq
+is an empty sequence.
+
 .coNP Accessor @ nthcdr
 .synb
 .mets (nthcdr < index << list )