68c006a95b
This PR enables transforming nondependent `let`s into `have`s in a number of contexts: the bodies of nonrecursive definitions, equation lemmas, smart unfolding definitions, and types of theorems. A motivation for this change is that when zeta reduction is disabled, `simp` can only effectively rewrite `have` expressions (e.g. `split` uses `simp` with zeta reduction disabled), and so we cache the nondependence calculations by transforming `let`s to `have`s. The transformation can be disabled using `set_option cleanup.letToHave false`. Uses `Meta.letToHave`, introduced in #8954.
63 lines
1.7 KiB
Text
63 lines
1.7 KiB
Text
axiom Std.HashMap : Type
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axiom Std.HashMap.insert : Std.HashMap → Std.HashMap
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axiom Std.HashMap.get? : Std.HashMap → Int → Option Unit
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structure St where
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m : Unit
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map : Std.HashMap
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opaque P : St → Prop
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noncomputable
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def go1 (ss : Int) (st0 : St) : Bool :=
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let st1 := { st0 with map := st0.map.insert }
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match st1.map.get? ss with
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| some _ =>
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have : P st1 := sorry
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have : P st1 := sorry
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go1 ss st1
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| none => true
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termination_by st0
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decreasing_by sorry
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/--
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info: go1.induct (ss : Int) (motive : St → Prop)
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(case1 :
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∀ (x : St),
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have st1 := { m := x.m, map := x.map.insert };
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∀ (val : Unit), st1.map.get? ss = some val → P st1 → P st1 → motive st1 → motive x)
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(case2 :
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∀ (x : St),
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have st1 := { m := x.m, map := x.map.insert };
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st1.map.get? ss = none → motive x)
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(st0 : St) : motive st0
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-/
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#guard_msgs in
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#check go1.induct
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-- the above was the original bugreport, and a (spurious) mdata around the match
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-- triggered a bug and looking through it solved it. But that would just hide it, and it
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-- can be triggered like this:
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noncomputable
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def go2 (ss : Int) (st0 : St) : Bool :=
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let st1 := { st0 with map := st0.map.insert }
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id <| match st1.map.get? ss with -- the ss argument is needed
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| some _ =>
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have : P st1 := sorry -- both needed
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have : P st1 := sorry -- both needed
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go2 ss st1
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| none => true
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termination_by st0
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decreasing_by sorry
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/--
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info: go2.induct : ∀ (motive : St → Prop),
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(∀ (x : St),
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have st1 := { m := x.m, map := x.map.insert };
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motive st1 → motive x) →
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∀ (st0 : St), motive st0
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-/
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#guard_msgs in
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#check @go2.induct
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