28cf146d00
This PR fixes a bug where the monad lift coercion elaborator would partially unify expressions even if they were not monads. This could be taken advantage of to propagate information that could help elaboration make progress, for example the first `change` worked because the monad lift coercion elaborator was unifying `@Eq _ _` with `@Eq (Nat × Nat) p`: ```lean example (p : Nat × Nat) : p = p := by change _ = ⟨_, _⟩ -- used to work (yielding `p = (p.fst, p.snd)`), now it doesn't change ⟨_, _⟩ = _ -- never worked ``` As such, this is a breaking change; you may need to adjust expressions to include additional implicit arguments.
51 lines
1.1 KiB
Text
51 lines
1.1 KiB
Text
set_option pp.mvars false
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structure Note where
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pitch : UInt64
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start : Nat
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def Note.containsNote (n1 n2 : Note) : Prop :=
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n1.start ≤ n2.start
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def Note.lowerSemitone (n : Note) : Note :=
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{ n with pitch := n.pitch - 1 }
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theorem Note.self_containsNote_lowerSemitone_self (n : Note) :
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n.containsNote (Note.lowerSemitone n) := by
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simp [Note.containsNote, Note.lowerSemitone]
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/--
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error: type mismatch
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rfl
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has type
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?_ = ?_ : Prop
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but is expected to have type
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n = n - 1 : Prop
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-/
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#guard_msgs in
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set_option maxRecDepth 100 in
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set_option maxHeartbeats 200 in
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example (n : UInt64) : n = n - 1 :=
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rfl
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namespace Ex2
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def lowerSemitone := fun (n : Note) => Note.mk (n.1 - 0) n.2
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set_option maxRecDepth 100 in
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theorem Note.self_containsNote_lowerSemitone_self (n : Note) :
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0 ≤ (lowerSemitone n).start :=
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(Nat.zero_le (Note.start n))
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end Ex2
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namespace Ex3
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def lowerSemitone := fun (n : Note) => Note.mk (n.1 + 100) n.2
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set_option maxRecDepth 200 in
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theorem Note.self_containsNote_lowerSemitone_self (n : Note) :
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0 ≤ (lowerSemitone n).start :=
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(Nat.zero_le (Note.start n))
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end Ex3
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