New function: arithp.

* lib.h (arithp): Declared.
(plus_s): Existing symbol declared.

* arith.c (arithp): New function.

* struct.h (special_slot): New enum member plus_m.

* struct.c (special_sym): Register plus_s together as
the [plus_m] entry of the array.

* tests/016/arith.tl
* tests/016/ud-arith.tl: Tests for arithp.

* txr.1: Documented.

* stdlib/doc-syms.tl: Updated.

1 files changed, 2 insertions, 0 deletions

diff --git a/lib.h b/lib.h
index f3cd8429..f7e6f992 100644
--- a/lib.h
+++ b/lib.h
@@ -689,6 +689,7 @@ extern val warning_s, defr_warning_s, restart_s, continue_s;
 extern val gensym_counter_s, length_s;
 extern val rplaca_s, rplacd_s, seq_iter_s;
 extern val lazy_streams_s;
+extern val plus_s;
 
 #define gensym_counter (deref(lookup_var_l(nil, gensym_counter_s)))
 
@@ -919,6 +920,7 @@ val bignump(val num);
 val floatp(val num);
 val integerp(val num);
 val numberp(val num);
+val arithp(val obj);
 val nary_op(val self, val (*bfun)(val, val),
             val (*ufun)(val self, val),
             struct args *args, val emptyval);