refactor: simplify SimpM recursive definitions
#3120
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src/Lean/Expr.lean
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| loop : Nat → Expr → Array Expr → Array Expr | ||
| | 0, _, as => as | ||
| | i+1, .app f a, as => loop i f (as.set! i a) | ||
| | _, _, as => as |
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This will return an array with dummy entries if there aren't enough arguments, will it? Maybe worth pointing out in the docs, also on which side the dummies are? Or maybe just panic instead, its probably misuse if n is too small?
| match n, e with | ||
| | 0, _ => e | ||
| | n+1, .app f _ => extractNumArgs f n | ||
| | _, _ => e |
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I'm a bit confused by the naming; this doesn't extract the args, but extracts the function, or strips the args, doesn't it?
The new test exposes a performance problem found in software verification applications.
See new test for example that takes exponential time without new simp theorems. TODO: replace auxiliary theorems with simprocs as soon as we implement them.
The example was looping with the new `simp` reduction strategy. Here is the looping trace. ``` List.reverseAux (List.reverseAux as []) bs ==> rewrite using reverseAux_reverseAux List.reverseAux [] (List.reverseAux (List.reverseAux as []) bs) ==> unfold reverseAux List.reverseAux (List.reverseAux as []) bs ==> rewrite using reverseAux_reverseAux List.reverseAux [] (List.reverseAux (List.reverseAux as []) bs) ==> ... ```
Motivations: - We can simplify the big mutual recursion and the implementation. - We can implement the support for `match`-expressions in the `pre` method. - It is easier to define and simplify `Simprocs`.
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| @[simp ↓] theorem ite_cond_true {_ : Decidable c} (a b : α) (h : c) : (if c then a else b) = a := by simp [h] | ||
| @[simp ↓] theorem ite_cond_false {_ : Decidable c} (a b : α) (h : ¬ c) : (if c then a else b) = b := by simp [h] | ||
| @[simp ↓] theorem dite_cond_true {α : Sort u} {_ : Decidable c} {t : c → α} {e : ¬ c → α} (h : c) : (dite c t e) = t h := by simp [h] | ||
| @[simp ↓] theorem dite_cond_false {α : Sort u} {_ : Decidable c} {t : c → α} {e : ¬ c → α} (h : ¬ c) : (dite c t e) = e h := by simp [h] |
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What's the intended difference between these lemmas and if_pos/if_neg/dif_pos/dif_neg?
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See comment at 5b46fde
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Subsumed by #3124 |
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Depends on #3118.
It breaks
Std, but it is an easy fix.