102   case Num(i) => i"ldc $i"

   102   case Num(i) => i"ldc $i"

   103   case Var(s) => i"iload ${env(s)} \t\t; $s"

   103   case Var(s) => i"iload ${env(s)} \t\t; $s"

   104   case Aop(op, a1, a2) => 

   104   case Aop(op, a1, a2) => 

   105     compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_op(op)

   105     compile_aexp(a1, env) ++ compile_aexp(a2, env) ++ compile_op(op)

   106 }

   106 }

   108 

   107 

   109 // boolean expression compilation

   108 // boolean expression compilation

   110 //  - the jump-label is for where to jump if the condition is not true

   109 //  - the jump-label is for where to jump if the condition is not true

   111 def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match {

   110 def compile_bexp(b: BExp, env : Env, jmp: String) : String = b match {

   112   case True => ""

   111   case True => ""