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/lib.h b/lib.h
index 2c1e307c..69b7ea97 100644
--- a/lib.h
+++ b/lib.h
@@ -1442,6 +1442,7 @@ val set_from(val range, val from);
 val set_to(val range, val to);
 val in_range(val range, val num);
 val in_range_star(val range, val num);
+val rangeref(val range, val ind);
 void out_str_char(wchar_t ch, val out, int *semi_flag, int regex);
 val obj_print_impl(val obj, val out, val pretty, struct strm_ctx *);
 val obj_print(val obj, val stream, val pretty);