traversers-with-types.groovy

int => [plus,15][is,[mult,[plus,22][mult,[id]]][gt,2]][lt,17][is,[eq,true]]
 ^__ traverser is an int token.
    ^__ you pass him into the pipeline (inst DAG)
   
// he creates the following inst DAG below that is now type checked/inferred.  

bool{?} <= [plus,15][is,bool <= [mult,int <= [plus,15][plus,22][mult,int <= [plus,15][plus,22]]][gt,2]][lt,17][is,bool{?} <= [eq,true]]

instruction                                                                            domain        range   
------------------------------------------------------------------------------------------------------------
[plus,15]                                                                              int       =>  int     
[is,bool <= [mult,int <= [plus,15][plus,22][mult,int <= [plus,15][plus,22]]][gt,2]]    int       =>  int{?}  
 [mult,int <= [plus,15][plus,22][mult,int <= [plus,15][plus,22]]]                       int      =>   int    
  [plus,15]                                                                              int     =>    int   
  [plus,22]                                                                              int     =>    int   
  [mult,int <= [plus,15][plus,22]]                                                       int     =>    int   
   [plus,15]                                                                              int    =>     int  
   [plus,22]                                                                              int    =>     int  
 [gt,2]                                                                                 int      =>   bool   
[lt,17]                                                                                int{?}    =>  bool{?} 
[is,bool{?} <= [eq,true]]                                                              bool{?}   =>  bool{?} 
 [eq,true]                                                                              bool{?}  =>   bool{?}