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Escaping Locations

• Answer produced by block contains location:
  • begin proc P =
       begin var A: newint;
          proc Q(X: intexp) = A:=X in Q end
    in (call P)(2) end
  • Answer of P is parameterized procedure.
  • P: intexp -> comm!
• Location of A escapes P
  • A bound to loc_i.
  • Answer of P is procedure q that updates loc_i.
  • q v s = [[mypi -U- {A: intloc, X: intexp} |- A:=X: comm]]
       (e -U- {A=loc_i, X=v}) s
    = update(loc_i, v, s)
• Current typing system prevents this!

Escaping locations must not be freed!