(λs.match s with
[ inl _ ⇒ false | inr s2 ⇒ halt sig M2 s2]).
-notation "a · b" non associative with precedence 65 for @{ 'middot $a $b}.
+notation "a · b" right associative with precedence 65 for @{ 'middot $a $b}.
interpretation "sequential composition" 'middot a b = (seq ? a b).
definition lift_confL ≝