26 lines
620 B
Text
26 lines
620 B
Text
set_option pp.notation false
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inductive [class] C (A : Type*)
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| mk : A → C
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definition val {A : Type*} (c : C A) : A :=
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C.rec (λa, a) c
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constant magic (A : Type*) : A
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attribute [instance, priority std.priority.max]
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noncomputable definition C_magic (A : Type*) : C A :=
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C.mk (magic A)
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attribute [instance]
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definition C_prop : C Prop :=
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C.mk true
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attribute [instance]
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definition C_prod {A B : Type*} (Ha : C A) (Hb : C B) : C (prod A B) :=
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C.mk (prod.mk (val Ha) (val Hb))
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-- C_magic will be used because it has max priority
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noncomputable definition test : C (prod Prop Prop) :=
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by tactic.apply_instance
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eval test
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