0cb79868f4
This PR adds “sparse casesOn” constructions. They are similar to `.casesOn`, but have arms only for some constructors and a catch-all (providing `t.ctorIdx ≠ 42` assumptions). The compiler has native support for these constructors and now (because of the similarity) also the per-constructor elimination principles.
51 lines
1.4 KiB
Text
51 lines
1.4 KiB
Text
inductive Vec (α : Type) : Nat → Type where
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| nil : Vec α 0
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| cons {n} : α → Vec α n → Vec α (n + 1)
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/--
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info: @[reducible] protected def Vec.nil.elim.{u} : {α : Type} →
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{motive : (a : Nat) → Vec α a → Sort u} → {a : Nat} → (t : Vec α a) → t.ctorIdx = 0 → motive 0 Vec.nil → motive a t
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-/
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#guard_msgs in
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#print sig Vec.nil.elim
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/--
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info: @[reducible] protected def Vec.cons.elim.{u} : {α : Type} →
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{motive : (a : Nat) → Vec α a → Sort u} →
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{a : Nat} →
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(t : Vec α a) →
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t.ctorIdx = 1 → ({n : Nat} → (a : α) → (a_1 : Vec α n) → motive (n + 1) (Vec.cons a a_1)) → motive a t
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-/
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#guard_msgs in
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#print sig Vec.cons.elim
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structure JustOneConstructor where
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(x : Nat)
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(y : Bool)
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/-- error: Unknown constant `JustOneConstructor.mk.elim` -/
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#guard_msgs in #print sig JustOneConstructor.mk.elim
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-- Test that the compiler compiles the ctorelim to straight line code
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set_option trace.Compiler.saveBase true
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/--
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trace: [Compiler.saveBase] size: 0
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def testDecl1 α motive a.1 t h nil : motive lcAny lcAny :=
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return nil
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-/
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#guard_msgs in
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def testDecl1 :=@Vec.nil.elim
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/--
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trace: [Compiler.saveBase] size: 3
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def testDecl2 α motive a.1 t h cons : motive lcAny lcAny :=
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cases t : motive lcAny lcAny
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| Vec.cons n a.2 a.3 =>
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let _x.4 := cons n a.2 a.3;
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return _x.4
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-/
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#guard_msgs in
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def testDecl2 := @Vec.cons.elim
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