Cannot find method 'compose'

gistfile1.txt

diff --git a/src/core/Mixy.pm b/src/core/Mixy.pm
index 4a09c38..9ee5338 100644
--- a/src/core/Mixy.pm
+++ b/src/core/Mixy.pm
@@ -29,21 +29,10 @@ my role Mixy does Baggy  {
         fail ".pick is not supported on a {self.^name}";
     }
 
-    multi method roll($count = 1) {
-        my @pairs = self.pairs.grep: *.value > 0;
-        my $total := [+] @pairs.map: *.value;
-        my $rolls = nqp::istype($count,Num)
-          ?? $total min $count !! nqp::istype($count,Whatever) ?? Inf !! $count;
-
-        sub roll-one ($ignore?){
-            my $rand = $total.rand;
-            my $seen = 0;
-            for @pairs -> $pair {
-                return $pair.key if ( $seen += $pair.value ) > $rand;
-            }
-        }
-
-        map &roll-one, 1 .. $rolls;
+    multi method roll(Mixy:D:) { Rakudo::Internals.WeightedRoll(self).roll }
+    multi method roll(Mixy:D: $count) {
+        my $roller = Rakudo::Internals.WeightedRoll(self);
+        map { $roller.roll-one }, 1 .. $count;
     }
 }
 
diff --git a/src/core/Rakudo/Internals.pm b/src/core/Rakudo/Internals.pm
index f46acb7..fa0d464 100644
--- a/src/core/Rakudo/Internals.pm
+++ b/src/core/Rakudo/Internals.pm
@@ -87,6 +87,31 @@ my class Rakudo::Internals {
             nqp::getcurhllsym("@END_PHASERS"));
         for @END -> $end { $end() };
     }
+
+    method WeightedRoll(\mix) {
+        class {
+            has @!pairs;
+            has $!total;
+
+            method BUILD(\mix) {
+                $!total = 0;
+                for mix.pairs {
+                    my $value := .value;
+                    if $value > 0 {
+                        @!pairs.push($_);
+                        $!total = $!total + $value;
+                    }
+                }
+                self
+            }
+            method new(\mix) { nqp::create(self).BUILD(mix) }
+            method roll() {
+                my $rand = $!total.rand;
+                my $seen = 0;
+                return .key if ( $seen = $seen + .value ) > $rand for @!pairs;
+            }
+        }.new(mix)
+    }
 }
 
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