[perl #63698] [PATCH] Reimplement List.reduce in Perl6.

[via RT]

# New Ticket Created by  Vasily Chekalkin 
# Please include the string:  [perl #63698]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=63698 >


---
 src/builtins/any-list.pir |   61 ---------------------------------------------
 src/setting/Any-list.pm   |   24 +++++++++++++++++
 2 files changed, 24 insertions(+), 61 deletions(-)


diff --git a/src/builtins/any-list.pir b/src/builtins/any-list.pir
index 1967fbf..b87666b 100644
--- a/src/builtins/any-list.pir
+++ b/src/builtins/any-list.pir
@@ -429,67 +429,6 @@ Return a List with the keys of the invocant.
     .tailcall self.'pick'($I0)
 .end
 
-=item reduce(...)
-
-=cut
-
-.namespace []
-.sub 'reduce' :multi('Sub')
-    .param pmc expression
-    .param pmc values          :slurpy
-    .tailcall values.'reduce'(expression)
-.end
-
-.namespace ['Any']
-.sub 'reduce' :method :multi(_, 'Sub')
-    .param pmc expression
-    .local pmc retv
-    .local pmc iter
-    .local pmc elem
-    .local pmc args
-    .local int i, arity
-
-    arity = expression.'arity'()
-    if arity < 2 goto error
-
-    iter = self.'iterator'()
-    unless iter goto empty
-    retv = shift iter
-  loop:
-    unless iter goto done
-
-    # Create arguments for closure
-    args = new 'ResizablePMCArray'
-    # Start with 1. First argument is result of previous call
-    i = 1
-
-  args_loop:
-    if i == arity goto invoke
-    unless iter goto elem_undef
-    elem = shift iter
-    goto push_elem
-  elem_undef:
-    elem = 'undef'()
-
-  push_elem:
-    push args, elem
-    inc i
-    goto args_loop
-
-  invoke:
-    retv = expression(retv, args :flat)
-    goto loop
-
-  empty:
-    .tailcall '!FAIL'('Cannot reduce an empty list')
-
-  error:
-    'die'('Cannot reduce() using a unary or nullary function.')
-
-  done:
-    .return(retv)
-.end
-
 
 =item sort()
 
diff --git a/src/setting/Any-list.pm b/src/setting/Any-list.pm
index 3849a86..5758dce 100644
--- a/src/setting/Any-list.pm
+++ b/src/setting/Any-list.pm
@@ -3,6 +3,26 @@ class Any is also {
         gather {
             take $_ if $test($_) for $values.list;
         }
+    };
+
+    multi method reduce( $values: Code $expression ) {
+        my $arity = $expression.arity;
+        die('Cannot reduce() using a unary or nullary function.') if $arity < 2;
+        
+        my @list = $values.list;
+        fail ('Cannot reduce() empty list') if @list.elems == 0;
+
+        my $res = shift @list;
+        $arity--;
+        while @list {
+            my @args = @list.splice(0, $arity);
+            if @args.elems < $arity {
+                # Extend args if list exausted early
+                @args.push(undef x ($arity - @args.elems));
+            }
+            $res = &$expression($res, |@args);
+        }
+        $res;
     }
 }
 
@@ -10,4 +30,8 @@ our List multi grep(Code $test, *...@values) {
     @values.grep($test)
 }
 
+multi reduce ( Code $expression ;; *...@values ) {
+    @values.reduce($expression);
+}
+
 # vim: ft=perl6