5f4e6a86d5
This PR updates the formatting of, and adds explanations for, "unknown identifier" errors as well as "failed to infer type" errors for binders and definitions. It attempts to ameliorate some of the confusion encountered in #1592 by modifying the wording of the "header is elaborated before body is processed" note and adding further discussion and examples of this behavior in the corresponding error explanation.
68 lines
1.3 KiB
Text
68 lines
1.3 KiB
Text
def fib : Nat → Nat
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| 0 => 0
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| 1 => 1
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| n+2 => fib n + fib (n+1)
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termination_by n => n
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/--
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error: tactic 'fail' failed
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⊢ fib 8 + fib (8 + 1) = 55
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-/
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#guard_msgs in
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example : fib 10 = 55 := by
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unfold fib
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fail
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def ack : Nat → Nat → Nat
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| 0, m => m + 1
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| n+1, 0 => ack n 1
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| n+1, m+1 => ack n (ack (n+1) m)
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termination_by n m => (n, m)
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/--
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error: tactic 'fail' failed
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⊢ ack 1 (ack (1 + 1) 1) = 7
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-/
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#guard_msgs in
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example : ack 2 2 = 7 := by
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unfold ack
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fail
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-- This checks that we can unfold definitions in the prelude
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/--
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error: tactic 'fail' failed
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α : Type u_1
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as : Array α
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i : Nat
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j : Fin as.size
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⊢ (if i < ↑j then
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let j' := ⟨↑j - 1, ⋯⟩;
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let as_1 := as.swap ↑j' ↑j ⋯ ⋯;
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insertIdx.loop i as_1 ⟨↑j', ⋯⟩
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else as).size =
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as.size
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-/
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#guard_msgs in
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@[simp] private theorem Array.size_insertIdx_loop (as : Array α) (i : Nat) (j : Fin as.size) :
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(insertIdx.loop i as j).size = as.size := by
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unfold insertIdx.loop
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fail
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theorem fib_eq_fib (n : Nat) : n ≤ fib (n + 2) :=
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match h : n with
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| 0 => by simp [fib]
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| 1 => by simp [fib]
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| n+2 => by
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have := fib_eq_fib n
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have := fib_eq_fib (n+1)
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simp only [fib] at *
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omega
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termination_by n
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-- This should not exist!
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/-- error: Unknown constant `fib_eq_fib.eq_def` -/
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#guard_msgs in
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#check fib_eq_fib.eq_def
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