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authorRyan Lahfa2024-05-15 15:11:42 +0200
committerRyan Lahfa2024-05-21 10:42:15 +0200
commit065e60754084ef169fd17bbb7ab1b492fb7497c3 (patch)
treea47a7ea9f04c31d197e2c1198bada4c4ac932369 /backends/lean/Base/Primitives
parentcbf425d178f9063507585233ebee7ca785567e3a (diff)
feat(backends/lean): make `max`-related coercions nicer
Situations where you have `coe (max a b) = max (coe a) (coe b)` are often stuck during verification because of the lack of this theorem. With this theorem, `push_cast` works as intended and normalizes even further. Signed-off-by: Ryan Lahfa <ryan.lahfa@inria.fr>
Diffstat (limited to 'backends/lean/Base/Primitives')
-rw-r--r--backends/lean/Base/Primitives/Scalar.lean12
1 files changed, 12 insertions, 0 deletions
diff --git a/backends/lean/Base/Primitives/Scalar.lean b/backends/lean/Base/Primitives/Scalar.lean
index dccbcdf2..f08b8dec 100644
--- a/backends/lean/Base/Primitives/Scalar.lean
+++ b/backends/lean/Base/Primitives/Scalar.lean
@@ -1419,6 +1419,18 @@ instance (ty: ScalarTy) : LinearOrder (Scalar ty) where
right; exact (Scalar.le_equiv _ _).2 H
decidableLE := ScalarDecidableLE ty
+-- Coercion theorems
+-- This is helpful whenever you want to "push" casts to the innermost nodes
+-- and make the cast normalization happen more magically.
+
+@[simp, norm_cast]
+theorem coe_max {ty: ScalarTy} (a b: Scalar ty): ↑(Max.max a b) = (Max.max (↑a) (↑b): ℤ) := by
+ -- TODO: there should be a shorter way to prove this.
+ rw [max_def, max_def]
+ split_ifs <;> simp_all
+ refine' absurd _ (lt_irrefl a)
+ exact lt_of_le_of_lt (by assumption) ((Scalar.lt_equiv _ _).2 (by assumption))
+
-- Leading zeros
def core.num.Usize.leading_zeros (x : Usize) : U32 := sorry
def core.num.U8.leading_zeros (x : U8) : U32 := sorry