x
x
x


Do so in a way which:

 does not involve string manipulation of the input source code
 is plausibly extensible to a runtime-chosen set of bindings rather than just x
 does not make x a global variable


or note that these are impossible.



See also

 For more general examples and language-specific details, see Eval.
 Dynamic variable names is a similar task.


import macros, strformat
 
macro eval(s, x: static[string]): untyped =
  parseStmt(&"let x={x}\n{s}")
 
echo(eval("x+1", "3.1"))