quote do::

• Builds an AST by shorthand, but lets you write Nim code as if it were regular code.

• Use quote do: to turn your code into the corresponding NimNode structure.

Backticks (x):

• refer to the original identifier within the quoted block;

• inject the original identifier (not a value) into the generated code.

Backticks work differently with templates/macros in Nim:

• Templates don't use backticks. The parameter name (expr) is used directly, as you're not working with the AST - you're doing direct code replacement/substitution.

• Macros use backticks. With macros, you're working with ASTs. Thus parameters like expr are not variables - they are NimNode(s).

  • The resulting code (x = x * 2) is generated and inserted at the macro call site.

  • Compare - this 'works', but it's not using the NimNode itself!

    x = x * 2
    

  • Whereas if I write this:

    template double(expr: untyped): untyped = 
      expr = expr * 2
    echo m, " ", double(m), " ", m
    

    See the resulting error, because of how/where the generated code appears (due to substitution): m = m *2