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.
77 lines
1.4 KiB
Text
77 lines
1.4 KiB
Text
namespace Ex1
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mutual
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def f : Nat → α → α → α
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| 0, a, b => a
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| n, a, b => g a n b |>.1
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termination_by n _ _ => (n, 2)
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decreasing_by
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simp_wf
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apply Prod.Lex.right
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decide
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def g : α → Nat → α → (α × α)
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| a, 0, b => (a, b)
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| a, n, b => (h a b n, a)
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termination_by _ n _ => (n, 1)
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decreasing_by
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simp_wf
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apply Prod.Lex.right
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decide
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def h : α → α → Nat → α
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| _a, b, 0 => b
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| a, b, n+1 => f n a b
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termination_by _ _ n => (n, 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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end
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#eval f 5 'a' 'b'
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#print f
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#print g
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#print h
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#print f._unary._mutual
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end Ex1
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namespace Ex2
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mutual
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def f : Nat → α → α → α
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| 0, a, b => a
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| n, a, b => g a n b |>.1
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termination_by n _ _ => (n, 2)
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def g : α → Nat → α → (α × α)
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| a, 0, b => (a, b)
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| a, n, b => (h a b n, a)
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termination_by _ n _ => (n, 1)
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def h : α → α → Nat → α
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| a, b, 0 => b
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| a, b, n+1 => f n a b
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termination_by _ _ n => (n, 0)
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end
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#print f._unary._mutual
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end Ex2
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namespace Ex3
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mutual
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def f : Nat → α → α → α
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| 0, a, b => a
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| n, a, b => g a n b |>.1
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def g : α → Nat → α → (α × α)
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| a, 0, b => (a, b)
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| a, n, b => (h a b n, a)
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def h : α → α → Nat → α
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| a, b, 0 => b
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| a, b, n+1 => f n a b
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end
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#print f._unary._mutual
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end Ex3
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