deb3299263
This PR changes the `simpMatch` function, used inside the equation generator for WF-rec functions, to not do eta-expansion. This makes the process a bit more robust and disciplined, and avoids removing match-statements (and introduce projections and dependencies) that we'd rather split instead. Also adds more tracing to the equational theorem generator. Extracted from #6898.
58 lines
1.6 KiB
Text
58 lines
1.6 KiB
Text
import Lean
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def foo (n : Nat) (f : Fin n) := match f with | ⟨k, _hk⟩ => if k == 0 then true else false
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def thm : foo n f = (if f.val == 0 then true else false) := by simp [foo]
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-- NB: equational theorem only applies if motive is manifest constructor
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/--
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info: foo.match_1.eq_1.{u_1} (n : Nat) (motive : Fin n → Sort u_1) (k : Nat) (_hk : k < n)
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(h_1 : (k : Nat) → (_hk : k < n) → motive ⟨k, _hk⟩) :
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(match ⟨k, _hk⟩ with
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| ⟨k, _hk⟩ => h_1 k _hk) =
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h_1 k _hk
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-/
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#guard_msgs in
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#check foo.match_1.eq_1
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open Lean Meta Elab Term
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elab "simpMatch" t:term : command => do
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Command.runTermElabM fun _ => do
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withDeclName `_simpMatch do
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let e ← elabTerm t none
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synthesizeSyntheticMVarsNoPostponing (ignoreStuckTC := false)
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let e' ← instantiateMVars e
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let r ← Split.simpMatch e'
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logInfo m!"{indentExpr e}\n==>{indentExpr r.expr}"
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-- This should simplify
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/--
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info:
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fun n f =>
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match ⟨↑f, ⋯⟩ with
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| ⟨k, _hk⟩ => if (k == 0) = true then true else false
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==>
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fun n f => if (↑f == 0) = true then true else false
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-/
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#guard_msgs in
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simpMatch
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fun (n : Nat) (f : Fin n) => (match Fin.mk f.val f.isLt with | ⟨k, _hk⟩ => if k == 0 then true else false)
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-- But this should not
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/--
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info:
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fun n f =>
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match f with
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| ⟨k, _hk⟩ => if (k == 0) = true then true else false
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==>
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fun n f =>
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match f with
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| ⟨k, _hk⟩ => if (k == 0) = true then true else false
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-/
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#guard_msgs in
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simpMatch
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fun (n : Nat) (f : Fin n) => (match f with | ⟨k, _hk⟩ => if k == 0 then true else false)
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