From 10083ef8d5be31db094ce70d0021d23aecdb9249 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sat, 14 Apr 2012 21:50:12 -0700
Subject: * eval.c (eval_init): find-if intrinsic registered.

* lib.c (find): First and second arguments reversed.
The item should be first.
(find_if): New function.

* lib.h (find): Declaration updated.
(find_if): Declaration added.

* txr.1: Stub section.
---
 ChangeLog | 13 +++++++++++++
 eval.c    |  1 +
 lib.c     | 31 ++++++++++++++++++++++++++-----
 lib.h     |  1 +
 txr.1     |  2 +-
 5 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 46374ede..d8fda790 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2012-04-14  Kaz Kylheku  <kaz@kylheku.com>
+
+	* eval.c (eval_init): find-if intrinsic registered.
+
+	* lib.c (find): First and second arguments reversed.
+	The item should be first.
+	(find_if): New function.
+
+	* lib.h (find): Declaration updated.
+	(find_if): Declaration added.
+
+	* txr.1: Stub section.
+
 2012-04-14  Kaz Kylheku  <kaz@kylheku.com>
 
 	* HACKING: Added notes on generational garbage collection.
diff --git a/eval.c b/eval.c
index aab58a61..3cacebb5 100644
--- a/eval.c
+++ b/eval.c
@@ -2374,6 +2374,7 @@ void eval_init(void)
   reg_fun(intern(lit("merge"), user_package), func_n4o(merge, 2));
   reg_fun(intern(lit("sort"), user_package), func_n3o(sort, 2));
   reg_fun(intern(lit("find"), user_package), func_n4o(find, 2));
+  reg_fun(intern(lit("find-if"), user_package), func_n3o(find_if, 2));
   reg_fun(intern(lit("set-diff"), user_package), func_n4o(set_diff, 2));
 
   reg_fun(intern(lit("length"), user_package), func_n1(length));
diff --git a/lib.c b/lib.c
index 7e42361a..704c0bd0 100644
--- a/lib.c
+++ b/lib.c
@@ -3944,21 +3944,42 @@ val sort(val seq, val lessfun, val keyfun)
   return seq;
 }
 
-val find(val list, val key, val testfun, val keyfun)
+val find(val item, val list, val testfun, val keyfun)
 {
-  uses_or2;
+  if (!keyfun)
+    keyfun = identity_f;
+
+  if (!testfun)
+    testfun = equal_f;
+
+  for (; list; list = cdr(list)) {
+    val elem = car(list);
+    val key = funcall1(keyfun, elem);
+
+    if (funcall2(testfun, item, key))
+      return elem;
+  }
+
+  return nil;
+}
+
+val find_if(val pred, val list, val key)
+{
+  if (!key)
+    key = identity_f;
 
   for (; list; list = cdr(list)) {
     val item = car(list);
-    val list_key = funcall1(or2(keyfun, identity_f), item);
+    val subj = funcall1(key, item);
 
-    if (funcall2(or2(testfun, equal_f), key, list_key))
+    if (funcall1(pred, subj))
       return item;
   }
 
   return nil;
 }
 
+
 val set_diff(val list1, val list2, val testfun, val keyfun)
 {
   list_collect_decl (out, ptail);
@@ -3978,7 +3999,7 @@ val set_diff(val list1, val list2, val testfun, val keyfun)
       val item = car(list1);
       val list1_key = funcall1(keyfun, item);
 
-      if (!find(list2, list1_key, testfun, keyfun))
+      if (!find(list1_key, list2, testfun, keyfun))
         list_collect (ptail, item);
     }
   }
diff --git a/lib.h b/lib.h
index e6c72b1e..ed500b40 100644
--- a/lib.h
+++ b/lib.h
@@ -631,6 +631,7 @@ val mappend(val fun, val list);
 val merge(val list1, val list2, val lessfun, val keyfun);
 val sort(val seq, val lessfun, val keyfun);
 val find(val list, val key, val testfun, val keyfun);
+val find_if(val pred, val list, val key);
 val set_diff(val list1, val list2, val testfun, val keyfun);
 val length(val seq);
 val sub(val seq, val from, val to);
diff --git a/txr.1 b/txr.1
index 487e10da..6a84a6be 100644
--- a/txr.1
+++ b/txr.1
@@ -7564,7 +7564,7 @@ Examples:
 
 .SS Function sort
 
-.SS Function find
+.SS Functions find and find-if
 
 .SS Function set-diff
 
-- 
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