5a24cb5ef7
@Kha `hygienicIntro` is true by default. `hygienicIntro == false` is the Lean3 behavior. If we find `hygienicIntro` too inconvenient in practice, we set the default to false.
47 lines
1.2 KiB
Text
47 lines
1.2 KiB
Text
new_frontend
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set_option hygienicIntro false in
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theorem ex1 {a p q r : Prop} : p → (p → q) → (q → r) → r := by
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intro _ h1 h2;
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apply h2;
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apply h1;
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exact a_1 -- Bad practice, using name generated by `intro`.
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theorem ex2 {a p q r : Prop} : p → (p → q) → (q → r) → r := by
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intro _ h1 h2;
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apply h2;
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apply h1;
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exact a_1 -- error "unknown identifier"
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theorem ex3 {a p q r : Prop} : p → (p → q) → (q → r) → r := by
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intro _ h1 h2;
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apply h2;
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apply h1;
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assumption
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂;
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{ apply h₁; exact h }; -- error "unknown identifier"
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exact h
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set_option hygienicIntro false in
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂;
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{ apply h₁; exact h }; -- hygiene is disabled
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exact h
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-- Hygienic versions
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂ with
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| inl h => apply h₁; exact h
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| inr h => exact h
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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cases h₂;
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{ apply h₁; assumption };
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assumption
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example {p q : Prop} (h₁ : p → q) (h₂ : p ∨ q) : q := by
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match h₂ with
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| Or.inl _ => apply h₁; assumption
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| Or.inr h => exact h
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