af6d2077a0
This PR changes how match splitters are generated: Rather than rewriting the match statement, the match compilation pipeline is used again. The benefits are: * Re-doing the match compilation means we can do more intelligent book keeping, e.g. prove overlap assumptions only once and re-use the proof, or prune the context of the MVar to speed up `contradiction`. This may have allowed a different solution than #11200. * It would unblock #11105, as the existing splitter implementation would have trouble dealing with the matchers produced that way. * It provides the necessary machinery also for source-exposed “none of the above” bindings, a feature that we probably want at some point (and we mostly need to find good syntax for, see #3136, although maybe I should open a dedicated RFC). * It allows us to skip costly things during matcher creation that would only be useful for the splitter, and thus allows performance improvements like #11508. * We can drop the existing implementation. It’s not entirely free: * We have to run `simpH` twice, once for the match equations and once for the splitter.
104 lines
4 KiB
Text
104 lines
4 KiB
Text
import Lean
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open Lean Expr Level -- just for shorter outpt
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-- set_option trace.Meta.Match.match true
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-- set_option trace.Meta.Match.debug true
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-- set_option trace.Meta.Tactic.induction true
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def simple : Lean.Expr → Bool
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| .sort _ => true
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| _ => false
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/--
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info: def simple.match_1.{u_1} : (motive : Expr → Sort u_1) →
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(x : Expr) → ((u : Level) → motive (sort u)) → ((x : Expr) → motive x) → motive x :=
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fun motive x h_1 h_2 => simple._sparseCasesOn_1 x (fun u => h_1 u) fun h => h_2 x
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-/
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#guard_msgs in
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#print simple.match_1
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-- Check that the splitter re-uses the sparseCasesOn generated for the matcher:
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/--
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info: private def simple.match_1.splitter.{u_1} : (motive : Expr → Sort u_1) →
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(x : Expr) →
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((u : Level) → motive (sort u)) → ((x : Expr) → (∀ (u : Level), x = sort u → False) → motive x) → motive x :=
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fun motive x h_1 h_2 => simple._sparseCasesOn_1 x (fun u => h_1 u) fun h => h_2 x ⋯
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-/
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#guard_msgs in
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#print simple.match_1.splitter
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def expensive : Lean.Expr → Lean.Expr → Bool
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| .app (.app (.sort 1) (.sort 1)) (.sort 1), .app (.app (.sort 1) (.sort 1)) (.sort 1) => false
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| _, _ => true
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/-- info: false -/
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#guard_msgs in
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#eval expensive (.app (.app (.sort 1) (.sort 1)) (.sort 1)) (.app (.app (.sort 1) (.sort 1)) (.sort 1))
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/-- info: true -/
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#guard_msgs in
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#eval expensive (.app (.app (.sort 2) (.sort 1)) (.sort 1)) (.app (.app (.sort 1) (.sort 1)) (.sort 1))
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example : expensive (.app (.app (.sort 1) (.sort 1)) (.sort 1)) (.app (.app (.sort 1) (.sort 1)) (.sort 1)) = false := rfl
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example : expensive (.app (.app (.sort 2) (.sort 1)) (.sort 1)) (.app (.app (.sort 1) (.sort 1)) (.sort 1)) = true := rfl
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/--
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info: expensive.match_1.{u_1} (motive : Expr → Expr → Sort u_1) (x✝ x✝¹ : Expr)
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(h_1 :
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Unit →
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motive (((sort zero.succ).app (sort zero.succ)).app (sort zero.succ))
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(((sort zero.succ).app (sort zero.succ)).app (sort zero.succ)))
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(h_2 : (x x_1 : Expr) → motive x x_1) : motive x✝ x✝¹
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-/
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#guard_msgs in
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#check expensive.match_1
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/--
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info: expensive.match_1.splitter.{u_1} (motive : Expr → Expr → Sort u_1) (x✝ x✝¹ : Expr)
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(h_1 :
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Unit →
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motive (((sort zero.succ).app (sort zero.succ)).app (sort zero.succ))
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(((sort zero.succ).app (sort zero.succ)).app (sort zero.succ)))
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(h_2 :
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(x x_1 : Expr) →
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(x = ((sort zero.succ).app (sort zero.succ)).app (sort zero.succ) →
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x_1 = ((sort zero.succ).app (sort zero.succ)).app (sort zero.succ) → False) →
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motive x x_1) :
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motive x✝ x✝¹
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-/
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#guard_msgs in
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#check expensive.match_1.splitter
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/--
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info: expensive.match_1.eq_1.{u_1} (motive : Expr → Expr → Sort u_1)
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(h_1 :
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Unit →
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motive (((sort zero.succ).app (sort zero.succ)).app (sort zero.succ))
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(((sort zero.succ).app (sort zero.succ)).app (sort zero.succ)))
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(h_2 : (x x_1 : Expr) → motive x x_1) :
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(match ((sort zero.succ).app (sort zero.succ)).app (sort zero.succ),
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((sort zero.succ).app (sort zero.succ)).app (sort zero.succ) with
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| ((sort zero.succ).app (sort zero.succ)).app (sort zero.succ),
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((sort zero.succ).app (sort zero.succ)).app (sort zero.succ) => h_1 ()
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| x, x_1 => h_2 x x_1) =
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h_1 ()
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-/
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#guard_msgs in
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#check expensive.match_1.eq_1
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/--
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info: expensive.match_1.eq_2.{u_1} (motive : Expr → Expr → Sort u_1) (x✝ x✝¹ : Expr)
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(h_1 :
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Unit →
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motive (((sort zero.succ).app (sort zero.succ)).app (sort zero.succ))
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(((sort zero.succ).app (sort zero.succ)).app (sort zero.succ)))
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(h_2 : (x x_1 : Expr) → motive x x_1) :
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(x✝ = ((sort zero.succ).app (sort zero.succ)).app (sort zero.succ) →
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x✝¹ = ((sort zero.succ).app (sort zero.succ)).app (sort zero.succ) → False) →
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(match x✝, x✝¹ with
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| ((sort zero.succ).app (sort zero.succ)).app (sort zero.succ),
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((sort zero.succ).app (sort zero.succ)).app (sort zero.succ) => h_1 ()
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| x, x_1 => h_2 x x_1) =
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h_2 x✝ x✝¹
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-/
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#guard_msgs in
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#check expensive.match_1.eq_2
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