b5122b6a7b
This change * moves `termination_by` and `decreasing_by` next to the function they apply to * simplify the syntax of `termination_by` * apply the `decreasing_by` goal to all goals at once, for better interactive use. See the section in `RELEASES.md` for more details and migration advise. This is a hard breaking change, requiring developers to touch every `termination_by` in their code base. We decided to still do it as a hard-breaking change, because supporting both old and new syntax at the same time would be non-trivial, and not save that much. Moreover, this requires changes to some metaprograms that developers might have written, and supporting both syntaxes at the same time would make _their_ migration harder.
40 lines
703 B
Text
40 lines
703 B
Text
import Lean
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open Lean
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open Lean.Meta
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def tst (declName : Name) : MetaM Unit := do
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IO.println (← getUnfoldEqnFor? declName)
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mutual
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def g (i j : Nat) : Nat :=
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if i < 5 then 0 else
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match j with
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| Nat.zero => 1
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| Nat.succ j => h i j
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termination_by (i + j, 0)
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decreasing_by
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simp_wf
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· apply Prod.Lex.left
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apply Nat.lt_succ_self
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def h (i j : Nat) : Nat :=
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match j with
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| 0 => g i 0
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| Nat.succ j => g i j
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termination_by (i + j, 1)
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decreasing_by
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all_goals simp_wf
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· apply Prod.Lex.right
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decide
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· apply Prod.Lex.left
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apply Nat.lt_succ_self
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end
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#eval tst ``g
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#check g._eq_1
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#check g._eq_2
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#check g._unfold
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#eval tst ``h
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#check h._eq_1
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#check h._eq_2
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#check h._unfold
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