New function: rangeref.

Because ranges can be iterated like sequences, and are
identified as vector-like, they have to support indexing.
However, ranges already have semantics as a function:
with a sequence argument, they slice it.

Let's put the semantics into a function called rangeref,
so it can be coherently documented.

* eval.c (eval_init): Register rangeref intrinsic.

* lib.c (generic_funcall): Range as a function works in
terms of rangeref.
(ref): Handle RNG case via rangeref.
(rangeref): New function.

* lib.h (rangeref): Declared.

* tests/012/seq.tl: New tests.

1 files changed, 1 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index e6edb5a0..095313ac 100644
--- a/eval.c
+++ b/eval.c
@@ -7830,6 +7830,7 @@ void eval_init(void)
   reg_fun(intern(lit("to"), user_package), func_n1(to));
   reg_fun(intern(lit("in-range"), user_package), func_n2(in_range));
   reg_fun(intern(lit("in-range*"), user_package), func_n2(in_range_star));
+  reg_fun(intern(lit("rangeref"), user_package), func_n2(rangeref));
 
   reg_fun(intern(lit("make-like"), user_package), func_n2(make_like));
   reg_fun(intern(lit("nullify"), user_package), func_n1(nullify));