A good start on the macro idea

I call it macro because it lets you insert basically arbitrary risc code into the ruby level. The way it works:
Reserve namespace X
map any X.some_call to a Mom instruction
by the name SomeCall
which must take the same args in constructor as given
And obviously produce whatever risc it wants
Hoping to rewrite builtin around this idea (with the existing Mom builtn instructions)

lib/vool/if_statement.rb

@@ -15,12 +15,11 @@ module Vool
       false_label = Mom::Label.new( self , "false_label_#{object_id.to_s(16)}")
       merge_label = Mom::Label.new( self , "merge_label_#{object_id.to_s(16)}")
 
-      check =  Mom::TruthCheck.new(condition.to_slot(compiler) , false_label)
       if @condition.is_a?(CallStatement)
         head = @condition.to_mom(compiler)
-        head << check
+        head << check_slot(compiler , false_label)
       else
-        head = check
+        head = check_slot(compiler , false_label)
       end
       head << true_label
       head << if_true.to_mom(compiler)   if @if_true
@@ -31,6 +30,11 @@ module Vool
       head
     end
 
+    # create the slot lazily, so to_mom gets called first
+    def check_slot(compiler , false_label)
+      Mom::TruthCheck.new(@condition.to_slot(compiler) , false_label)
+    end
+
     def each(&block)
       block.call(condition)
       @if_true.each(&block) if @if_true