Allow adding none and anything

src/eval/ops.rs

@@ -61,6 +61,9 @@ pub fn neg(value: Value) -> StrResult<Value> {
 /// Compute the sum of two values.
 pub fn add(lhs: Value, rhs: Value) -> StrResult<Value> {
     Ok(match (lhs, rhs) {
+        (a, None) => a,
+        (None, b) => b,
+
         (Int(a), Int(b)) => Int(a + b),
         (Int(a), Float(b)) => Float(a as f64 + b),
         (Float(a), Int(b)) => Float(a + b as f64),
@@ -83,9 +86,6 @@ pub fn add(lhs: Value, rhs: Value) -> StrResult<Value> {
         (Fraction(a), Fraction(b)) => Fraction(a + b),
 
         (Str(a), Str(b)) => Str(a + b),
-
-        (Content(a), None) => Content(a),
-        (None, Content(b)) => Content(b),
         (Content(a), Content(b)) => Content(a + b),
         (Content(a), Str(b)) => Content(a + model::Content::Text(b)),
         (Str(a), Content(b)) => Content(model::Content::Text(a) + b),

tests/typ/code/dict.typ

@@ -39,8 +39,8 @@
 // Missing lvalue is automatically none-initialized.
 {
   let dict = (:)
-  // Error: 3-17 cannot add none and integer
   dict("b") += 1
+  test(dict, (b: 1))
 }
 
 ---

tests/typ/code/ops.typ

@@ -27,6 +27,8 @@
 // Addition.
 #test(2 + 4, 6)
 #test("a" + "b", "ab")
+#test("a" + if false { "b" }, "a")
+#test("a" + if true { "b" }, "ab")
 #test(13 * "a" + "bbbbbb", "aaaaaaaaaaaaabbbbbb")
 #test((1, 2) + (3, 4), (1, 2, 3, 4))
 #test((a: 1) + (b: 2, c: 3), (a: 1, b: 2, c: 3))