0db6daa8f1
I did a bad git rebase before merging #5283, which reverted it to an earlier version. This PR has the actual implementation of RFC #5397.
68 lines
1.2 KiB
Text
68 lines
1.2 KiB
Text
inductive Exp
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| hole
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| var (i : UInt32)
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| app (a b : Exp)
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with
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/-- Computes the hash -/ @[simp, computed_field] protected hash : Exp → UInt64
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| .var i => Hashable.hash i
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| .app a b => mixHash a.hash b.hash
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| .hole => 32
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def dagLikeTerm : Nat → Exp
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| 0 => .app (.var 42) .hole
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| n+1 => .app (dagLikeTerm n) (dagLikeTerm n)
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#guard (dagLikeTerm 1000).hash == 10432648428259852868 -- memoized
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def varNum? : Exp → Option UInt32
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| .var i => i
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| _ => none
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example : varNum? (.var 32) = some 32 := by native_decide
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namespace WithIndices
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inductive B.C (α : Type u) : Nat → Type u
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| a : C α 0
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| b (c : C α n) {d : C α (n-1)} : C α (n+1)
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with
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@[computed_field] hash : ∀ α i, C α i → UInt64
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| _, _, .a => 1
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| _, _, .b c => 42 + c.hash _ _
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#guard (B.C.b (α := Nat) (.a) (d := .a)).hash _ _ == 43
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end WithIndices
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namespace Mutual
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mutual
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inductive A
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| a (b : B)
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| b (b : B)
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with
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@[computed_field] f : A → Nat
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| .a c => 32 + c.f
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| .b c => 42 + 2*c.f
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inductive B
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| c (a : A)
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| d
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with
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@[computed_field] f : B → Nat
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| .c a => a.f
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| .d => 0
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end
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#guard (B.c (.a .d)).f == 32
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end Mutual
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