From 5cfb638fd129ee5d139c69c2ddf06da67c5612b6 Mon Sep 17 00:00:00 2001
From: Luchs <Luchs@euirc.eu>
Date: Fri, 16 Jan 2015 09:24:18 +0100
Subject: [PATCH] Use @munificent's single-argument reduce

---
 builtin/core.wren                 | 13 ++++++++++++-
 src/wren_core.c                   | 13 ++++++++++++-
 test/list/reduce_single_item.wren |  3 ++-
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/builtin/core.wren b/builtin/core.wren
index 5baf4e5b..dc8a9888 100644
--- a/builtin/core.wren
+++ b/builtin/core.wren
@@ -29,7 +29,18 @@ class Sequence {
     return acc
   }
 
-  reduce(f) { this[1..-1].reduce(this[0], f) }
+  reduce(f) {
+    var iter = iterate(null)
+    if (!iter) Fiber.abort("Can't reduce an empty sequence.")
+
+    // Seed with the first element.
+    var result = iteratorValue(iter)
+    while (iter = iterate(iter)) {
+      result = f.call(result, iteratorValue(iter))
+    }
+
+    return result
+  }
 
 }
 
diff --git a/src/wren_core.c b/src/wren_core.c
index 8699d4d8..71762347 100644
--- a/src/wren_core.c
+++ b/src/wren_core.c
@@ -72,7 +72,18 @@ static const char* libSource =
 "    return acc\n"
 "  }\n"
 "\n"
-"  reduce(f) { this[1..-1].reduce(this[0], f) }\n"
+"  reduce(f) {\n"
+"    var iter = iterate(null)\n"
+"    if (!iter) Fiber.abort(\"Can't reduce an empty sequence.\")\n"
+"\n"
+"    // Seed with the first element.\n"
+"    var result = iteratorValue(iter)\n"
+"    while (iter = iterate(iter)) {\n"
+"      result = f.call(result, iteratorValue(iter))\n"
+"    }\n"
+"\n"
+"    return result\n"
+"  }\n"
 "\n"
 "}\n"
 "\n"
diff --git a/test/list/reduce_single_item.wren b/test/list/reduce_single_item.wren
index 195778f4..0f874c99 100644
--- a/test/list/reduce_single_item.wren
+++ b/test/list/reduce_single_item.wren
@@ -1 +1,2 @@
-[1].reduce {|a, b| a } // expect runtime error: Range start out of bounds.
+IO.print([1].reduce {|a, b| 42 }) // expect: 1
+IO.print([].reduce(1) {|a, b| 42 }) // expect: 1