33 lines
591 B
Text
33 lines
591 B
Text
new_frontend
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class Inc (α : Type) :=
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(inc : α → α)
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export Inc (inc)
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instance {α} [Inc α] : Inc (List α) :=
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{ inc := (·.map inc) }
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instance : Inc Nat :=
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{ inc := Nat.succ }
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#eval inc 10
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#eval inc [1, 2, 3]
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theorem ex1 : [(1, "hello"), (2, "world")].map (·.1) = [1, 2] :=
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rfl
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theorem ex2 : [(1, "hello"), (2, "world")].map (·.snd) = ["hello", "world"] :=
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rfl
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def sum (xs : List Nat) : Nat :=
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(·.2) $ Id.run $ StateT.run (s:=0) do
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xs.forM fun x => modify (· + x)
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#eval sum [1, 2, 3, 4]
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theorem ex3 : sum [1, 2, 3] = 6 :=
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rfl
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theorem ex4 : sum [1, 2, 3, 4] = 10 :=
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rfl
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