424fbbdf26
This PR adds the ability to register theorems with the `cbv_eval` attribute in the reverse direction using the `←` modifier, mirroring the existing `simp` attribute behavior. When `@[cbv_eval ←]` is used, the equation `lhs = rhs` is inverted to `rhs = lhs`, allowing `cbv` to rewrite occurrences of `rhs` to `lhs`. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
59 lines
1.4 KiB
Text
59 lines
1.4 KiB
Text
import Std
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set_option cbv.warning false
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-- Basic test: inverted cbv_eval attribute
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-- The theorem `42 = myConst` with ← becomes `myConst = 42`
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-- so cbv can rewrite `myConst` to `42`
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@[cbv_opaque] def myConst : Nat := 42
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@[cbv_eval ←] theorem myConst_eq : 42 = myConst := by rfl
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example : myConst = 42 := by
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conv =>
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lhs
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cbv
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-- Test with a function application on the RHS
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def myAdd (a b : Nat) : Nat := a + b
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@[cbv_opaque] def myAddAlias (a b : Nat) : Nat := myAdd a b
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-- The theorem `myAdd a b = myAddAlias a b` with ← becomes `myAddAlias a b = myAdd a b`
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-- so cbv can rewrite `myAddAlias a b` to `myAdd a b`, which it can then evaluate
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@[cbv_eval ←] theorem myAddAlias_eq (a b : Nat) : myAdd a b = myAddAlias a b := by
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unfold myAddAlias; rfl
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example : myAddAlias 2 3 = 5 := by
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conv =>
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lhs
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cbv
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-- Test with <- syntax (alternative arrow)
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@[cbv_opaque] def myConst2 : Nat := 100
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@[cbv_eval <-] theorem myConst2_eq : 100 = myConst2 := by rfl
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example : myConst2 = 100 := by
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conv =>
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lhs
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cbv
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-- Test that non-inverted cbv_eval still works
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@[cbv_opaque] def myConst3 : Nat := 7
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@[cbv_eval] theorem myConst3_eq : myConst3 = 7 := by rfl
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example : 7 = 7 := by
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conv =>
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lhs
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cbv
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-- Test with the optional ident argument (backward compatibility)
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@[cbv_opaque] def myFn (n : Nat) : Nat := n + 1
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@[cbv_eval myFn] theorem myFn_zero : myFn 0 = 1 := by rfl
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example : 1 = 1 := by
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conv =>
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lhs
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cbv
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