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.
12 lines
591 B
Text
12 lines
591 B
Text
theorem Array.sizeOf_lt_of_mem' [DecidableEq α] [SizeOf α] {as : Array α} (h : as.contains a) : sizeOf a < sizeOf as := by
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simp [Membership.mem, contains, any, Id.run, BEq.beq, anyM] at h
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let rec aux (j : Nat) : anyM.loop (m := Id) (fun b => decide (a = b)) as as.size (Nat.le_refl ..) j = true → sizeOf a < sizeOf as := by
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unfold anyM.loop
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intro h
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split at h
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· simp [Bind.bind, pure] at h; split at h
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next he => subst a; apply sizeOf_get_lt
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next => have ih := aux (j+1) h; assumption
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· contradiction
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termination_by as.size - j
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apply aux 0 h
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