Add scoped quotation syntax for object-language programs

Introduce [spa_e| ... ] for Expr and [spa| ... ] for Stmt, scoped to the
Spa namespace via a dedicated syntax category and macro_rules. This removes
the deeply nested .andThen / .basic (.assign ...) boilerplate when writing
programs; Main.lean's test programs are rewritten to use it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lean/Main.lean

@@ -1,26 +1,30 @@
 import Spa.Analysis.Sign
 import Spa.Analysis.Constant
+import Spa.Language.Notation
 
 namespace Spa
 
-def testCode : Stmt :=
-  .andThen (.basic (.assign "zero" (.num 0)))
-    (.andThen (.basic (.assign "pos" (.add (.var "zero") (.num 1))))
-      (.andThen (.basic (.assign "neg" (.sub (.var "zero") (.num 1))))
-        (.basic (.assign "unknown" (.add (.var "pos") (.var "neg"))))))
+def testCode : Stmt := [obj_stmt|
+  zero    := 0;
+  pos     := zero + 1;
+  neg     := zero - 1;
+  unknown := pos + neg
+]
 
-def testCodeCond₁ : Stmt :=
-  .andThen (.basic (.assign "var" (.num 1)))
-    (.ifElse (.var "var")
-      (.basic (.assign "var" (.add (.var "var") (.num 1))))
-      (.andThen (.basic (.assign "var" (.sub (.var "var") (.num 1))))
-        (.basic (.assign "var" (.num 1)))))
+def testCodeCond₁ : Stmt := [obj_stmt|
+  var := 1;
+  if var {
+    var := var + 1
+  } else {
+    var := var - 1;
+    var := 1
+  }
+]
 
-def testCodeCond₂ : Stmt :=
-  .andThen (.basic (.assign "var" (.num 1)))
-    (.ifElse (.var "var")
-      (.basic (.assign "x" (.num 1)))
-      (.basic .noop))
+def testCodeCond₂ : Stmt := [obj_stmt|
+  var := 1;
+  if var { x := 1 } else { noop }
+]
 
 def testProgram : Program := ⟨testCode⟩
 

lean/Spa.lean

@@ -7,6 +7,7 @@ import Spa.Lattice.AboveBelow
 import Spa.Lattice.IterProd
 import Spa.Lattice.FiniteMap
 import Spa.Language.Base
+import Spa.Language.Notation
 import Spa.Language.Semantics
 import Spa.Language.Graphs
 import Spa.Language.Traces

lean/Spa/Language/Notation.lean

@@ -0,0 +1,60 @@
+import Spa.Language.Base
+
+namespace Spa
+
+/-!
+Scoped quotation syntax for writing object-language programs.
+
+`[obj_expr| … ]` builds an `Expr`, `[obj_stmt| … ]` builds a `Stmt`.
+
+Example:
+```
+[obj_stmt|
+  zero := 0;
+  pos  := zero + 1;
+  if pos { x := 1 } else { noop };
+  while x { x := x - 1 }
+]
+```
+-/
+
+/-- Expressions of the object language. -/
+declare_syntax_cat obj_expr
+
+syntax num                              : obj_expr
+syntax ident                           : obj_expr
+syntax:65 obj_expr:65 " + " obj_expr:66 : obj_expr
+syntax:65 obj_expr:65 " - " obj_expr:66 : obj_expr
+syntax "(" obj_expr ")"                 : obj_expr
+
+/-- Statements of the object language. -/
+declare_syntax_cat obj_stmt
+
+syntax "noop"                                          : obj_stmt
+syntax ident " := " obj_expr                           : obj_stmt
+syntax "if " obj_expr " { " obj_stmt " } " "else" " { " obj_stmt " } " : obj_stmt
+syntax "while " obj_expr " { " obj_stmt " } "          : obj_stmt
+syntax:50 obj_stmt:51 "; " obj_stmt:50                 : obj_stmt
+syntax "(" obj_stmt ")"                                : obj_stmt
+
+scoped syntax "[obj_expr| " obj_expr " ]" : term
+scoped syntax "[obj_stmt| " obj_stmt " ]" : term
+
+scoped macro_rules
+  | `([obj_expr| $n:num])        => `(Expr.num $n)
+  | `([obj_expr| $x:ident])      => `(Expr.var $(Lean.quote x.getId.toString))
+  | `([obj_expr| $a + $b])       => `(Expr.add [obj_expr| $a] [obj_expr| $b])
+  | `([obj_expr| $a - $b])       => `(Expr.sub [obj_expr| $a] [obj_expr| $b])
+  | `([obj_expr| ($e:obj_expr)]) => `([obj_expr| $e])
+
+scoped macro_rules
+  | `([obj_stmt| noop])           => `(Stmt.basic .noop)
+  | `([obj_stmt| $x:ident := $e]) =>
+      `(Stmt.basic (.assign $(Lean.quote x.getId.toString) [obj_expr| $e]))
+  | `([obj_stmt| $s₁ ; $s₂])      => `(Stmt.andThen [obj_stmt| $s₁] [obj_stmt| $s₂])
+  | `([obj_stmt| if $e { $s₁ } else { $s₂ }]) =>
+      `(Stmt.ifElse [obj_expr| $e] [obj_stmt| $s₁] [obj_stmt| $s₂])
+  | `([obj_stmt| while $e { $s }]) => `(Stmt.whileLoop [obj_expr| $e] [obj_stmt| $s])
+  | `([obj_stmt| ($s:obj_stmt)])  => `([obj_stmt| $s])
+
+end Spa