25 lines
348 B
Text
25 lines
348 B
Text
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open nat
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inductive expr :=
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| zero : expr
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| one : expr
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| add : expr → expr → expr
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namespace expr
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infix `+` := expr.add
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set_option pp.notation false
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definition ev : expr → nat
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| zero := 0
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| one := 1
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| #expr (a + b) := ev a + ev b
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definition foo : expr := add zero (add one one)
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example : ev foo = 2 :=
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rfl
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end expr
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