c9e4c89d9c
The tactic mk_dec_eq_instance constructs a function using the brec_on recursor. The compiler generates horrible code for this kind of definition. It creates a closure for each recursive call. Moreover, `brec_on` accumulates all intermediate results. To generate efficient code, we need to generate a collection of recursive equations, and then invoke the equation compiler. cc @kha
51 lines
1.6 KiB
Text
51 lines
1.6 KiB
Text
/-
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Copyright (c) 2018 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Sebastian Ullrich
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-/
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prelude
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import init.data
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-- non-meta instance
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instance : decidable_eq name :=
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sorry -- TODO(Leo): define instance after we implement new `decidable` type class
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universes u v w
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namespace name
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@[simp] protected def quick_lt : name → name → Prop
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| anonymous anonymous := false
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| anonymous _ := true
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| (mk_numeral v n) (mk_numeral v' n') := v < v' ∨ v = v' ∧ n.quick_lt n'
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| (mk_numeral _ _) (mk_string _ _) := true
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| (mk_string s n) (mk_string s' n') := s < s' ∨ s = s' ∧ n.quick_lt n'
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| _ _ := false
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instance decidable_rel_quick_lt : decidable_rel name.quick_lt :=
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begin
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intros n n',
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induction n generalizing n',
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case anonymous {
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by_cases n' = anonymous; simp *; apply_instance
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},
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all_goals { cases n'; {
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tactic.unfreeze_local_instances, -- use recursive instance
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simp; apply_instance } }
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end
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protected def has_lt_quick : has_lt name := ⟨name.quick_lt⟩
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end name
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namespace option
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variables {α : Type u} (r : α → α → Prop)
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@[simp] protected def lt : option α → option α → Prop
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| none (some x) := true
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| (some x) (some y) := r x y
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| _ _ := false
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instance decidable_rel_lt [decidable_rel r] : decidable_rel (option.lt r) :=
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by intros a b; cases a; cases b; simp; apply_instance
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protected def has_lt [has_lt α] : has_lt (option α) := ⟨option.lt (<)⟩
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end option
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