pretty-printer for not equal

2023-10-28 22:00:41 +02:00
parent b24987fc19
commit 14ce186239
3 changed files with 30 additions and 0 deletions
--- a/Game/Tactic/Ne.lean
+++ b/Game/Tactic/Ne.lean
@@ -0,0 +1,15 @@
+import Lean
+
+/-!
+A pretty-printer that displays `¬ (a = b)` as `a ≠ b`.
+-/
+
+open Lean PrettyPrinter Delaborator SubExpr
+
+@[delab app.Not] def delab_not_mem :=
+  whenPPOption Lean.getPPNotation do
+  let #[f] := (← SubExpr.getExpr).getAppArgs | failure
+  unless f.getAppFn matches .const `Eq _ do failure
+  let stx₁ ← SubExpr.withAppArg <| SubExpr.withNaryArg 1 delab
+  let stx₂ ← SubExpr.withAppArg <| SubExpr.withNaryArg 2 delab
+  return ← `($stx₁ ≠ $stx₂)