Change prefix:<+> to dispatch to .Numeric for all types which descend…

… from Mu. Define Mu.Numeric to return 0, Cool.Numeric to call the pir function to convert to a Num.

Still need to define Numeric.Numeric.

src/Perl6/Grammar.pm

@@ -1603,7 +1603,7 @@ token postfix:sym«->» {
 
 token infix:sym<**>   { <sym>  <O('%exponentiation')> }
 
-token prefix:sym<+>   { <sym>  <O('%symbolic_unary, :pirop<set N*>')> }
+token prefix:sym<+>   { <sym>  <O('%symbolic_unary')> }
 token prefix:sym<~>   { <sym>  <O('%symbolic_unary')> }
 token prefix:sym<->   { <sym> <![>]> <O('%symbolic_unary')> }
 token prefix:sym<?>   { <!before '???'> <sym>  <O('%symbolic_unary')> }

src/cheats/num-ops.pir

@@ -34,3 +34,13 @@
     .return ($I0)
 .end
 
+.sub '&prefix:<+>'
+    .param pmc x
+    $I0 = isa x, ['Mu']
+    if $I0 goto p6_x
+    $N0 = x
+    .return ($N0)
+  p6_x:
+    $P0 = x.'Numeric'()
+    .return ($P0)
+.end

src/core/Cool-num.pm

@@ -1,4 +1,8 @@
 augment class Cool {
+    method Numeric() {
+        pir::set__NP(self);
+    }
+
     method abs() {
         (+self).abs;
     }

src/core/Mu.pm

@@ -1,6 +1,10 @@
 augment class Mu {
     method Bool { $.defined }
 
+    method Numeric { 0; } # Not sure if this makes sense or not
+                          # but there are several tests it makes
+                          # pass.
+
     method item {
         # This is overridden by non-items.
         self;