🐐 Various fixes

README.md

@@ -67,13 +67,13 @@ Strings are written as text in quotes (`'` or `"`).
 DESIGNA x VT "this is a string"
 ```
 
-Strings are concatenated with `:`:
+Strings are concatenated with `&`:
 
 ```
-DESIGNA greeting VT "Hello, " : "world!"
+DESIGNA greeting VT "Hello, " & "world!"
 ```
 
-`NVLLVS` coerces to an empty string when used with `:`. Note: `+` is for arithmetic only — using it on strings raises an error.
+`NVLLVS` coerces to an empty string when used with `&`. Note: `+` is for arithmetic only — using it on strings raises an error.
 
 ### Integers
 Integers must be written in roman numerals using the following symbols:
@@ -165,12 +165,13 @@ SI x TVNC {
 
 ```
 DESIGNA x VT II
-SI x EST I TVNC
+SI x EST I TVNC {
     DICE(I)
-ALVID SI x EST II TVNC
+} ALVID SI x EST II TVNC {
     DICE(II)
-ALVID
+} ALVID {
     DICE(III)
+}
 
 > II
 ```

centvrion/ast_nodes.py

@@ -259,9 +259,11 @@ class DataRangeArray(Node):
   def _eval(self, vtable):
     vtable, from_val = self.from_value.eval(vtable)
     vtable, to_val = self.to_value.eval(vtable)
-    if not isinstance(from_val, ValInt) or not isinstance(to_val, ValInt):
+    if not isinstance(from_val, (ValInt, ValNul)) or not isinstance(to_val, (ValInt, ValNul)):
       raise CentvrionError("Range bounds must be numbers")
-    return vtable, ValList([ValInt(i) for i in range(from_val.value(), to_val.value())])
+    from_int = from_val.value() or 0
+    to_int = to_val.value() or 0
+    return vtable, ValList([ValInt(i) for i in range(from_int, to_int)])
 
 
 class String(Node):
@@ -894,4 +896,6 @@ class Program(BaseBox):
     last_val = ValNul()
     for statement in self.statements:
       vtable, last_val = statement.eval(vtable)
+      if vtable["#return"] is not None:
+        return vtable["#return"]
     return last_val