483f32edd8
This feature produced counterintuitive behavior and confused users. See discussion at #770. As pointed out by @tydeu, it is not too much work to write `Id.run <|` before the `do` when we want to use the `do` notation in pure code. closes #770
19 lines
417 B
Text
19 lines
417 B
Text
universe u
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def f {α : Type u} [BEq α] (xs : List α) (y : α) : α := Id.run <| do
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for x in xs do
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if x == y then
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return x
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return y
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structure S :=
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(key val : Nat)
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instance : BEq S :=
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⟨fun a b => a.key == b.key⟩
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theorem ex1 : f (α := S) [⟨1, 2⟩, ⟨3, 4⟩, ⟨5, 6⟩] ⟨3, 0⟩ = ⟨3, 4⟩ :=
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rfl
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theorem ex2 : f (α := S) [⟨1, 2⟩, ⟨3, 4⟩, ⟨5, 6⟩] ⟨4, 10⟩ = ⟨4, 10⟩ :=
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rfl
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