b02c1c56ab
This commit also - improves `split` error messages. - adds `trace.split.failure` option. - uses new convention for trace messages. closes #4390
54 lines
1.6 KiB
Text
54 lines
1.6 KiB
Text
def step (state: Nat): Option Nat :=
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if state = 0 then none else some (state - 1)
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set_option linter.unusedVariables false
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def countdown (state: Nat) :=
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match h: step state with
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| none => [state]
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| some newState => state :: countdown newState
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termination_by state
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decreasing_by sorry
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/--
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error: tactic 'split' failed, consider using `set_option trace.split.failures true`
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state : Nat
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p :
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(match h : step state with
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| none => [state]
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| some newState => state :: countdown newState) ≠
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[]
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⊢ (match h : step state with
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| none => [state]
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| some newState => state :: countdown newState).head
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p =
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state
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---
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info: [split.failure] `split` tactic failed to generalize discriminant(s) at
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match h : step state with
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| none => [state]
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| some newState => state :: countdown newState
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resulting expression was not type correct
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possible solution: generalize discriminant(s) manually before using `split`
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-/
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#guard_msgs in
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example (state: Nat) (p : (match h : step state with
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| none => [state]
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| some newState => state :: countdown newState) ≠
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[]): (match h : step state with
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| none => [state]
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| some newState => state :: countdown newState).head
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p =
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state := by
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set_option trace.split.failure true in
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split
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example (state: Nat) (p : (match h : step state with
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| none => [state]
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| some newState => state :: countdown newState) ≠
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[]): (match h : step state with
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| none => [state]
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| some newState => state :: countdown newState).head
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p =
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state := by
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split at p <;> simp
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