New range type, distinct from cons cell.

* eval.c (eval_init): Register intrinsic functions rcons,
rangep from and to.
(eval_init): Register rangep intrinsic.

* gc.c (mark_obj): Traverse RNG objects.
(finalize): Handle RNG in switch.

* hash.c (equal_hash, eql_hash): Hashing for for RNG objects.

* lib.c (range_s, rcons_s): New symbol variables.
(code2type): Handle RNG type.
(eql, equal): Equality for ranges.
(less_tab_init): Table extended to cover RNG.
(less): Semantics defined for ranges.
(rcons, rangep, from, to): New functions.
(obj_init): range_s and rcons_s variables initialized.
(obj_print_impl): Produce #R notation for ranges.
(generic_funcall, dwim_set): Recognize range objects for indexing

* lib.h (enum type): New enum member, RNG.  MAXTYPE redefined
to RNG value.
(TYPE_SHIFT): Increased to 5 since there are now 16 type
codes.
(struct range): New struct type.
(union obj): New member rn, of type struct range.
(range_s, rcons_s, rcons, rangep, from, to): Declared.
(range_bind): New macro.

* parser.l (grammar): New rule for recognizing
the #R sequence as HASH_R token.

* parser.y (HASH_R): New terminal symbol.
(range): New nonterminal symbol.
(n_expr): Derives the new range symbol.
The n_expr DOTDOT n_expr rule produces rcons expression rather
than const.

* match.c (format_field): Recognize rcons syntax in fields
which is now what ranges translate to.  Also recognize range
object.

* tests/013/maze.tl (neigh): Fix code which destructures
range as a cons. That can't be done any more.

* txr.1: Document ranges.

1 files changed, 5 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index 052c7994..21e1dcea 100644
--- a/eval.c
+++ b/eval.c
@@ -4776,6 +4776,11 @@ void eval_init(void)
   reg_fun(intern(lit("where"), user_package), func_n2(where));
   reg_fun(intern(lit("select"), user_package), func_n2(sel));
 
+  reg_fun(intern(lit("rcons"), user_package), func_n2(rcons));
+  reg_fun(intern(lit("rangep"), user_package), func_n1(rangep));
+  reg_fun(intern(lit("from"), user_package), func_n1(from));
+  reg_fun(intern(lit("to"), user_package), func_n1(to));
+
   reg_fun(intern(lit("make-like"), user_package), func_n2(make_like));
   reg_fun(intern(lit("nullify"), user_package), func_n1(nullify));