From 638293d5281db1276a3b64f2eb969ad99c0ee9f3 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 22 Dec 2021 07:13:33 -0800
Subject: New functions: subq, subql, subqual and subst.

* eval.c (eval_init): Register new intrinsics.

* lib.c, lib.h (subq, subql, subqual, subst): New functions.

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

* stdlib/optimize.tl (subst): Function removed. The new subst
drop-in replaces this one.

* txr.1: Documented.

* stdlib/doc-syms.tl: Updated.
---
 lib.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

(limited to 'lib.c')

diff --git a/lib.c b/lib.c
index 79ad82a0..cce37b3a 100644
--- a/lib.c
+++ b/lib.c
@@ -11487,6 +11487,39 @@ val pos_min(val seq, val testfun, val keyfun)
   return pos_max(seq, default_arg(testfun, less_f), keyfun);
 }
 
+val subq(val oldv, val newv, val seq)
+{
+  return subst(oldv, newv, seq, eq_f, identity_f);
+}
+
+val subql(val oldv, val newv, val seq)
+{
+  return subst(oldv, newv, seq, eql_f, identity_f);
+}
+
+val subqual(val oldv, val newv, val seq)
+{
+  return subst(oldv, newv, seq, equal_f, identity_f);
+}
+
+val subst(val oldv, val newv, val seq, val testfun_in, val keyfun_in)
+{
+  val self = lit("subst");
+  seq_iter_t iter;
+  seq_iter_init(self, &iter, seq);
+  val elem;
+  val testfun = default_arg(testfun_in, equal_f);
+  val keyfun = default_arg(keyfun_in, identity_f);
+  list_collect_decl (out, ptail);
+
+  while (seq_get(&iter, &elem)) {
+    val key = funcall1(keyfun, elem);
+    ptail = list_collect(ptail, if3(funcall2(testfun, oldv, key), newv, elem));
+  }
+
+  return make_like(out, seq);
+}
+
 val mismatch(val left, val right, val testfun_in, val keyfun_in)
 {
   val testfun = default_arg(testfun_in, equal_f);
-- 
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