94 lines
2.9 KiB
Text
94 lines
2.9 KiB
Text
(**
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-- This example demonstrates how to create Macros for automating proof
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-- construction using Lua.
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-- This macro creates the syntax-sugar
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-- name bindings ',' expr
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-- For a function f with signature
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-- f : ... (A : Type) ... (Pi x : A, ...)
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--
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-- farity is the arity of f
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-- typepos is the position of (A : Type) argument
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-- lambdapos is the position of the (Pi x : A, ...) argument
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--
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-- Example: suppose we invoke
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--
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-- binder_macro("for", Const("ForallIntro"), 3, 1, 3)
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--
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-- Then, the macro expression
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--
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-- for x y : Int, H x y
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--
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-- produces the expression
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--
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-- ForallIntro Int _ (fun x : Int, ForallIntro Int _ (fun y : Int, H x y))
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--
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-- The _ are placeholders (aka) holes that will be filled by the Lean
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-- elaborator.
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function binder_macro(name, f, farity, typepos, lambdapos)
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macro(name, { macro_arg.Bindings, macro_arg.Comma, macro_arg.Expr },
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function (bindings, body)
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local r = body
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for i = #bindings, 1, -1 do
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local bname = bindings[i][1]
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local btype = bindings[i][2]
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local args = {}
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args[#args + 1] = f
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for j = 1, farity, 1 do
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if j == typepos then
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args[#args + 1] = btype
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elseif j == lambdapos then
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args[#args + 1] = fun(bname, btype, r)
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else
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args[#args + 1] = mk_placeholder()
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end
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end
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r = mk_app(unpack(args))
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end
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return r
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end)
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end
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function nary_macro(name, f, farity)
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local bin_app = function(e1, e2)
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local args = {}
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args[#args + 1] = f
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for i = 1, farity - 2, 1 do
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args[#args + 1] = mk_placeholder()
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end
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args[#args + 1] = e1
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args[#args + 1] = e2
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return mk_app(unpack(args))
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end
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macro(name, { macro_arg.Expr, macro_arg.Expr, macro_arg.Exprs },
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function (e1, e2, rest)
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local r = bin_app(e1, e2)
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for i = 1, #rest do
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r = bin_app(r, rest[i])
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end
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return r
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end)
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end
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binder_macro("for", Const("ForallIntro"), 3, 1, 3)
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binder_macro("assume", Const("Discharge"), 3, 1, 3)
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nary_macro("instantiate", Const("ForallElim"), 4)
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nary_macro("mp", Const("MP"), 4)
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**)
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Definition Set (A : Type) : Type := A → Bool
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Definition element {A : Type} (x : A) (s : Set A) := s x
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Infix 60 ∈ : element
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Definition subset {A : Type} (s1 : Set A) (s2 : Set A) := ∀ x, x ∈ s1 ⇒ x ∈ s2
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Infix 50 ⊆ : subset
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Theorem SubsetTrans (A : Type) : ∀ s1 s2 s3 : Set A, s1 ⊆ s2 ⇒ s2 ⊆ s3 ⇒ s1 ⊆ s3 :=
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for s1 s2 s3, assume (H1 : s1 ⊆ s2) (H2 : s2 ⊆ s3),
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show s1 ⊆ s3,
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for x, assume Hin : x ∈ s1,
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show x ∈ s3,
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let L1 : x ∈ s2 := mp (instantiate H1 x) Hin
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in mp (instantiate H2 x) L1
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