procedure execute(prog:tree);

#include "lazy.type.P"

   var evals, envcells, conscells :integer; { statistics }
       LastId :alfa;                 { debugging}
       Answer :Value;

   procedure error( m:alfa );
   begin writeln; writeln('Error: ', m, ' LastId=', LastId);
         goto 99  {error abort}
   end;

#include "lazy.mkval.P"   { Make various Values }

function eval( x:tree; rho:Env ):Value; forward;
procedure force( v:Value ); forward;

#include "lazy.env.P"     { manipulate Environment }
#include "lazy.D.P"       { Execute Declarations }
#include "lazy.apply.P"   { Apply a Function }
#include "lazy.U.P"       { Execute Unary Operators }
#include "lazy.O.P"       { Execute Binary Operators }
#include "lazy.eval.P"    { eval and force an Expression }
#include "lazy.show.P"    { Output Values }

begin{execute}
     evals := 0; envcells := 0; conscells := 0; {zero counters}
     LastId   := '-start-   ';
   Answer := defer(prog, {Env=}nil);
   ShowValue(Answer);  { Execution is print driven }
     writeln;
     write( evals,       ' evals, ');
     write( envcells,    ' env cells used, ');
     writeln( conscells, ' cells used')
end{execute};

{\fB Shell of Interpreter for Functional Language. \fP}

{Do not remove: Lazy.p, Strict.p, lazy.*.P, strict.*.P, lex.*.P, & syntax.*.P }
{ are released under Gnu `copyleft' General Public Licence (GPL)              }
{ - L. Allison, CSSE, Monash Uni., .au, 7/2003, 6/2017.                               }