make it a bit clearer where an exception was thrown

util/eval.py

@@ -1,22 +1,33 @@
 # based on https://stackoverflow.com/a/39381428
 # Parses and executes a block of Python code, and returns the eval result of the last statement
 
+from concrete_syntax.common import indent
+
 import ast
 def exec_then_eval(code, _globals={}, _locals={}):
-    block = ast.parse(code, mode='exec')
-    # assumes last node is an expression
-    last = ast.Expression(block.body.pop().value)
-    extended_globals = {
-        '__builtins__': __builtins__,
-        **_globals,
-    }
-    exec(compile(block, '<string>', mode='exec'), extended_globals, _locals)
-    return eval(compile(last, '<string>', mode='eval'), extended_globals, _locals)
+    try:
+        block = ast.parse(code, mode='exec')
+        # assumes last node is an expression
+        last = ast.Expression(block.body.pop().value)
+        extended_globals = {
+            '__builtins__': __builtins__,
+            **_globals,
+        }
+        exec(compile(block, '<string>', mode='exec'), extended_globals, _locals)
+        result = eval(compile(last, '<string>', mode='eval'), extended_globals, _locals)
+        return result
+    except Exception as e:
+        e.add_note("In the following user code fragment:\n"+indent(code, 4))
+        raise
 
 def simply_exec(code, _globals={}, _locals={}):
-    block = ast.parse(code, mode='exec')
-    extended_globals = {
-        '__builtins__': __builtins__,
-        **_globals,
-    }
-    exec(compile(block, '<string>', mode='exec'), extended_globals, _locals)
+    try:
+        block = ast.parse(code, mode='exec')
+        extended_globals = {
+            '__builtins__': __builtins__,
+            **_globals,
+        }
+        exec(compile(block, '<string>', mode='exec'), extended_globals, _locals)
+    except Exception as e:
+        e.add_note("In the following user code fragment:\n"+indent(code, 4))
+        raise