From a229461d0aff75401d3164c286a5f0960238199e Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Tue, 21 Jan 2014 21:27:49 -0800
Subject: * eval.c (mapcarv, mappendv): Convert output to type of leftmost
 input sequence.

* lib.c (make_like): New function.
(reverse, remq, remql, remqual, remove_if, keep_if, mapcar, mapcon,
mappend, set_diff): Convert output list to type of leftmost input
sequence.

* lib.h (make_like): Declared.

* txr.1: Documented.
---
 eval.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'eval.c')

diff --git a/eval.c b/eval.c
index e43bd2cc..8ac48da8 100644
--- a/eval.c
+++ b/eval.c
@@ -1828,6 +1828,7 @@ val mapcarv(val fun, val list_of_lists)
     return mapcar(fun, car(list_of_lists));
   } else {
     val lofl = copy_list(list_of_lists);
+    val list_orig = car(list_of_lists);
     list_collect_decl (out, otail);
 
     for (;;) {
@@ -1837,7 +1838,7 @@ val mapcarv(val fun, val list_of_lists)
       for (iter = lofl; iter; iter = cdr(iter)) {
         val list = car(iter);
         if (!list)
-          return out;
+          return make_like(out, list_orig);
         list_collect(atail, car(list));
         *car_l(iter) = cdr(list);
       }
@@ -1853,6 +1854,7 @@ static val mappendv(val fun, val list_of_lists)
     return mappend(fun, car(list_of_lists));
   } else {
     val lofl = copy_list(list_of_lists);
+    val list_orig = car(list_of_lists);
     list_collect_decl (out, otail);
 
     for (;;) {
@@ -1862,7 +1864,7 @@ static val mappendv(val fun, val list_of_lists)
       for (iter = lofl; iter; iter = cdr(iter)) {
         val list = car(iter);
         if (!list)
-          return out;
+          return make_like(out, list_orig);
         list_collect(atail, car(list));
         *car_l(iter) = cdr(list);
       }
-- 
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